Attempted to read or write protected memory when accessing dll

I try to access zip32.dll version 3.0 when my code got this error :

System.AccessViolationException: Attempted to read or write protected memory. 
This is often an indication that other memory is corrupt.
at projectName.clsName.ZpArchive(ZCL& zcl, ZPOPT& zopts)
at projectName.clsName.functionName() in <location>:<line>

This is what i done with the code :

//ZCL Structures
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
protected struct ZCL
{
    public int argc;                  /* Count of files to zip */
    [MarshalAs(UnmanagedType.LPStr)]
    public string fzname;             /* name of archive to create/update */
    public string[] zipnames;         /* zip file name */
    [MarshalAs(UnmanagedType.LPStr)]
    public string fzlist;             /* name of archive to create/update */
}

//ZPOPT Structures
[ StructLayout( LayoutKind.Sequential )]
            protected struct ZPOPT
            {
                  [MarshalAs(UnmanagedType.LPTStr)]
                  public string Date;                             // US Date (8 Bytes Long) "12/31/98"?
                  [MarshalAs(UnmanagedType.LPTStr)]
                  public string szRootDir;                  // Root Directory Pathname (Up To 256 Bytes Long)
                  [MarshalAs(UnmanagedType.LPTStr)]
                  public string szTempDir;                  // Temp Directory Pathname (Up To 256 Bytes Long)
                  public int fTemp;                         // 1 If Temp dir Wanted, Else 0
                  public int fSuffix;                             // Include Suffixes (Not Yet Implemented!)
                  public int fEncrypt;                            // 1 If Encryption Wanted, Else 0
                  public int fSystem;                             // 1 To Include System/Hidden Files, Else 0
                  public int fVolume;                             // 1 If Storing Volume Label, Else 0
                  public int fExtra;                                    // 1 If Excluding Extra Attributes, Else 0
                  public int fNoDirEntries;                 // 1 If Ignoring Directory Entries, Else 0
                  public int fExcludeDate;                  // 1 If Excluding Files Earlier Than Specified Date, Else 0
                  public int fIncludeDate;                  // 1 If Including Files Earlier Than Specified Date, Else 0
                  public int fVerbose;                            // 1 If Full Messages Wanted, Else 0
                  public int fQuiet;                                    // 1 If Minimum Messages Wanted, Else 0
                  public int fCRLF_LF;                      // 1 If Translate CR/LF To LF, Else 0
                  public int fLF_CRLF;                      // 1 If Translate LF To CR/LF, Else 0
                  public int fJunkDir;                            // 1 If Junking Directory Names, Else 0
                  public int fGrow;                               // 1 If Allow Appending To Zip File, Else 0
                  public int fForce;                                    // 1 If Making Entries Using DOS File Names, Else 0
                  public int fMove;                               // 1 If Deleting Files Added Or Updated, Else 0
                  public int fDeleteEntries;                // 1 If Files Passed Have To Be Deleted, Else 0
                  public int fUpdate;                             // 1 If Updating Zip File-Overwrite Only If Newer, Else 0
                  public int fFreshen;                            // 1 If Freshing Zip File-Overwrite Only, Else 0
                  public int fJunkSFX;                      // 1 If Junking SFX Prefix, Else 0
                  public int fLatestTime;                   // 1 If Setting Zip File Time To Time Of Latest File In Archive, Else 0
                  public int fComment;                      // 1 If Putting Comment In Zip File, Else 0
                  public int fOffsets;                            // 1 If Updating Archive Offsets For SFX Files, Else 0
                  public int fPrivilege;                    // 1 If Not Saving Privileges, Else 0
                  public int fEncryption;                   // Read Only Property!!!
                  public int fRecurse;                            // 1 (-r), 2 (-R) If Recursing Into Sub-Directories, Else 0
                  public int fRepair;                             // 1 = Fix Archive, 2 = Try Harder To Fix, Else 0
                  public byte flevel;                             // Compression Level - 0 = Stored 6 = Default 9 = Max
                  [MarshalAs(UnmanagedType.LPTStr)]
                  public string fSplitSize;                       //Null for no spliting size
                  //addition for ZCL
                  public int m_CountFile;                         //For total file on backup file.
            }

//Import Dll:
[DllImport("zip32.dll", SetLastError=true)]            
protected static extern int ZpArchive(ref ZCL zcl,ref ZPOPT zopts);

And here's the function that call the ZpArchive :

//set the zip options
              m_zopts = CreateZPOPTOptions();

              ZCL zcl = new ZCL();
              zcl.argc = m_CountFile; //Total file
              zcl.fzname = m_ZipFileName;
              zcl.zipnames = m_FilesToZip;
              zcl.fzlist = null;

              //zip the files
              try
              {
                  ret = ZpArchive(ref zcl,ref m_zopts);
              }
              catch(Exception e)
              {
                    //<catch>
              }

The exception threw when i try to call the ZpArchive function. I'm using Visual Studio 2010 with compatibility for .Net 2.0 Any idea / advise regarding to this issue?

Thanks in advance :) -FDI

Update :

Here's the structure from library source code :

typedef struct {        /* zip options */
LPSTR Date;             /* Date to include after */
LPSTR szRootDir;        /* Directory to use as base for zipping */
LPSTR szTempDir;        /* Temporary directory used during zipping */
BOOL fTemp;             /* Use temporary directory '-b' during zipping */
BOOL fSuffix;           /* include suffixes (not implemented) */
BOOL fEncrypt;          /* encrypt files */
BOOL fSystem;           /* includ开发者_如何学Pythone system and hidden files */
BOOL fVolume;           /* Include volume label */
BOOL fExtra;            /* Exclude extra attributes */
BOOL fNoDirEntries;     /* Do not add directory entries */
BOOL fExcludeDate;      /* Exclude files newer than specified date */
BOOL fIncludeDate;      /* Include only files newer than specified date */
BOOL fVerbose;          /* Mention oddities in zip file structure */
BOOL fQuiet;            /* Quiet operation */
BOOL fCRLF_LF;          /* Translate CR/LF to LF */
BOOL fLF_CRLF;          /* Translate LF to CR/LF */
BOOL fJunkDir;          /* Junk directory names */
BOOL fGrow;             /* Allow appending to a zip file */
BOOL fForce;            /* Make entries using DOS names (k for Katz) */
BOOL fMove;             /* Delete files added or updated in zip file */
BOOL fDeleteEntries;    /* Delete files from zip file */
BOOL fUpdate;           /* Update zip file--overwrite only if newer */
BOOL fFreshen;          /* Freshen zip file--overwrite only */
BOOL fJunkSFX;          /* Junk SFX prefix */
BOOL fLatestTime;       /* Set zip file time to time of latest file in it */
BOOL fComment;          /* Put comment in zip file */
BOOL fOffsets;          /* Update archive offsets for SFX files */
BOOL fPrivilege;        /* Use privileges (WIN32 only) */
BOOL fEncryption;       /* TRUE if encryption supported, else FALSE.
                           this is a read only flag */
LPSTR szSplitSize;      /* This string contains the size that you want to
                           split the archive into. i.e. 100 for 100 bytes,
                           2K for 2 k bytes, where K is 1024, m for meg
                           and g for gig. If this string is not NULL it
                           will automatically be assumed that you wish to
                           split an archive. */
LPSTR szIncludeList;    /* Pointer to include file list string (for VB) */
long IncludeListCount;  /* Count of file names in the include list array */
char **IncludeList;     /* Pointer to include file list array. Note that the last
                           entry in the array must be NULL */
LPSTR szExcludeList;    /* Pointer to exclude file list (for VB) */
long ExcludeListCount;  /* Count of file names in the include list array */
char **ExcludeList;     /* Pointer to exclude file list array. Note that the last
                           entry in the array must be NULL */
int  fRecurse;          /* Recurse into subdirectories. 1 => -r, 2 => -R */
int  fRepair;           /* Repair archive. 1 => -F, 2 => -FF */
char fLevel;            /* Compression level (0 - 9) */
} ZPOPT, _far *LPZPOPT;

typedef struct {
  int  argc;            /* Count of files to zip */
  LPSTR lpszZipFN;      /* name of archive to create/update */
  char **FNV;           /* array of file names to zip up */
  LPSTR lpszAltFNL;     /* pointer to a string containing a list of file
                           names to zip up, separated by whitespace. Intended
                           for use only by VB users, all others should set this
                           to NULL. */
} ZCL, _far *LPZCL;

and the function declaration :

int   EXPENTRY ZpArchive(ZCL C, LPZPOPT Opts);

some forum said it's because of umanageable code. I already use MarshalAs but still not working..