안드로이드 라이브월페이퍼 만들다가 오류가났어요..(로그캣 첨부)

08-04 14:06:07.500: ERROR/AndroidRuntime(369): FATAL EXCEPTION: main
08-04 14:06:07.500: ERROR/AndroidRuntime(369): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{girl.wallpaper/girl.wallpaper.Girl}: java.lang.ClassCastException: girl.wallpaper.Girl
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.os.Looper.loop(Looper.java:123)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread.main(ActivityThread.java:4627)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at java.lang.reflect.Method.invokeNative(Native Method)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at java.lang.reflect.Method.invoke(Method.java:521)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at dalvik.system.NativeStart.main(Native Method)
08-04 14:06:07.500: ERROR/AndroidRuntime(369): Caused by: java.lang.ClassCastException: girl.wallpaper.Girl
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
08-04 14:06:07.500: ERROR/AndroidRuntime(369):     ... 11 more

이게 뭔말인가여..