Failed to install apk file in android?

I am installing apk file in android emulator. But when I gave the command ADB INSTALL CALENDAR.APK in开发者_如何学编程 command prompt it is displaying the error as Failure [INSTALL_PARSE_FAILED_NO_CERTIFICATES]. What would be the reason? Can anybody help me regarding this?

Thank you,

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All Android packages must be signed to be installed, well at least since version 1.6. So that particular package is presumably older. You can get a newer one (or recompile yourself if you have the sources), or use an older version in your emulator (1.5).