com.jcraft.jsch.JSchException: Auth cancel, when connecting to my MAC

I am using the below target from ANT to connect t开发者_如何学JAVAo my MAC machine from Win XP.

<sshexec host="ip"
         username="user"
         password="pwd"
         trust="true"
         command="ps"/>

But sometime it works and i get the output, but some times (8 out of 10 executions) gives me com.jcraft.jsch.JSchException: Auth cancel exception.

So, this error is not coming all the time.

Can anyone help to identify the issue ?