我更新了最新的 ADT 捆绑包和 google play 服务库。之后，我尝试运行以前工作的项目。但这一次不能在设备上运行。LogCat 上的消息如下所示。出了什么问题，运行上一个项目我缺少哪一部分？
06-15 13:36:32.785: E/AndroidRuntime(30862): FATAL EXCEPTION: main
06-15 13:36:32.785: E/AndroidRuntime(30862): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{sg.SanThit.TrackMe/sg.SanThit.TrackMe.MainActivity}: java.lang.ClassNotFoundException: sg.SanThit.TrackMe.MainActivity
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2024)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread.access$600(ActivityThread.java:140)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.os.Handler.dispatchMessage(Handler.java:99)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.os.Looper.loop(Looper.java:137)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread.main(ActivityThread.java:4898)
06-15 13:36:32.785: E/AndroidRuntime(30862): at java.lang.reflect.Method.invokeNative(Native Method)
06-15 13:36:32.785: E/AndroidRuntime(30862): at java.lang.reflect.Method.invoke(Method.java:511)
06-15 13:36:32.785: E/AndroidRuntime(30862): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1008)
06-15 13:36:32.785: E/AndroidRuntime(30862): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:775)
06-15 13:36:32.785: E/AndroidRuntime(30862): at dalvik.system.NativeStart.main(Native Method)
06-15 13:36:32.785: E/AndroidRuntime(30862): Caused by: java.lang.ClassNotFoundException: sg.SanThit.TrackMe.MainActivity
06-15 13:36:32.785: E/AndroidRuntime(30862): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
06-15 13:36:32.785: E/AndroidRuntime(30862): at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
06-15 13:36:32.785: E/AndroidRuntime(30862): at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
06-15 13:36:32.785: E/AndroidRuntime(30862): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2015)
06-15 13:36:32.785: E/AndroidRuntime(30862): ... 11 more