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,

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).