Activity에서 FragmentActivity를 인텐트를 이용하여 새로 띄우고 싶은데 안되네요...

이렇게 developer에는 FragmentActivity가 Activity를 상속받는걸로 나와서
Activity 내 버튼을 누르면 detail 메소드가 실행이 되고 안의 startActivity를 이용하여 FragmentActivity를 실행하도록
public void detail(View view){
Intent intent = new Intent(this,Detail.class);
startActivity(intent);
}
위의 소스처럼 했는데 어플이 중지가 됩니다.
Detail.java가 FragmentActivity입니다.
아래는 로그입니다.
첫번째 줄에 보시다시피 detail 메소드안의 Detail 클래스를 찾지 못한다고 하네요...
FragmentActivity는 일반 Activity와 완전 다른걸까요?
08-07 22:36:02.716: E/dalvikvm(26611): Could not find class 'com.example.smartdriverlicense.Detail', referenced from method com.example.smartdriverlicense.CurrentPoint.detail
08-07 22:36:02.716: W/dalvikvm(26611): VFY: unable to resolve const-class 91 (Lcom/example/smartdriverlicense/Detail;) in Lcom/example/smartdriverlicense/CurrentPoint;
08-07 22:36:02.716: D/dalvikvm(26611): VFY: replacing opcode 0x1c at 0x0002
08-07 22:36:02.841: D/dalvikvm(26611): GC_CONCURRENT freed 359K, 14% free 10658K/12359K, paused 4ms+33ms, total 124ms
08-07 22:36:02.871: E/SpannableStringBuilder(26611): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
08-07 22:36:02.871: E/SpannableStringBuilder(26611): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
08-07 22:36:03.536: D/current(26611): thNVev8rOY
08-07 22:36:05.526: D/AndroidRuntime(26611): Shutting down VM
08-07 22:36:05.526: W/dalvikvm(26611): threadid=1: thread exiting with uncaught exception (group=0x40f6c2a0)
08-07 22:36:05.561: E/AndroidRuntime(26611): FATAL EXCEPTION: main
08-07 22:36:05.561: E/AndroidRuntime(26611): java.lang.IllegalStateException: Could not execute method of the activity
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.view.View$1.onClick(View.java:3704)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.view.View.performClick(View.java:4232)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.view.View$PerformClick.run(View.java:17298)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.os.Handler.handleCallback(Handler.java:615)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.os.Handler.dispatchMessage(Handler.java:92)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.os.Looper.loop(Looper.java:137)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.app.ActivityThread.main(ActivityThread.java:4921)
08-07 22:36:05.561: E/AndroidRuntime(26611): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 22:36:05.561: E/AndroidRuntime(26611): at java.lang.reflect.Method.invoke(Method.java:511)
08-07 22:36:05.561: E/AndroidRuntime(26611): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
08-07 22:36:05.561: E/AndroidRuntime(26611): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
08-07 22:36:05.561: E/AndroidRuntime(26611): at dalvik.system.NativeStart.main(Native Method)
08-07 22:36:05.561: E/AndroidRuntime(26611): Caused by: java.lang.reflect.InvocationTargetException
08-07 22:36:05.561: E/AndroidRuntime(26611): at java.lang.reflect.Method.invokeNative(Native Method)
08-07 22:36:05.561: E/AndroidRuntime(26611): at java.lang.reflect.Method.invoke(Method.java:511)
08-07 22:36:05.561: E/AndroidRuntime(26611): at android.view.View$1.onClick(View.java:3699)
08-07 22:36:05.561: E/AndroidRuntime(26611): ... 11 more
08-07 22:36:05.561: E/AndroidRuntime(26611): Caused by: java.lang.NoClassDefFoundError: com.example.smartdriverlicense.Detail
08-07 22:36:05.561: E/AndroidRuntime(26611): at com.example.smartdriverlicense.CurrentPoint.detail(CurrentPoint.java:82)
08-07 22:36:05.561: E/AndroidRuntime(26611): ... 14 more