如题，我在eclipse下一次导入源码中的Calculator、Calendar、CameraOpen、DeskClock等工程，右键项目Run as - Android Application，能正常启动模拟器（2.3的），但是在控制台下显示报错，提示：
[2012-03-07 14:17:17 - DeskClock] HOME is up on device 'emulator-5554'
[2012-03-07 14:17:17 - DeskClock] Uploading DeskClock.apk onto device 'emulator-5554'
[2012-03-07 14:17:24 - DeskClock] Installing DeskClock.apk...
[2012-03-07 14:17:43 - DeskClock] Re-installation failed due to different application signatures.
[2012-03-07 14:17:43 - DeskClock] You must perform a full uninstall of the application. WARNING: This will remove the application data!
[2012-03-07 14:17:43 - DeskClock] Please execute 'adb uninstall com.android.deskclock' in a shell.
[2012-03-07 14:17:43 - DeskClock] Launch canceled!
尝试解决：根据错误提示，说是这个Calculator已经存在，需要删除？ 于是我在dos下进入sdb目录下，一次执行如下命令：
adb remount -- remount succeeded
adb shell rm system/app/Calculator.apk -- rm failed for system/app/DeskClock.apk, Directory not empty
adb uninstall com.android.deskclock -- Failure
求解释，求答案...