otto使用报错

小弟在使用square/otto报错，具体如情况如下：

操作系统为window7,手机模拟器和真实的机器都试过，都不行。
具体情况如下：

我在MainActivity中是这样写的(跟官方的sample很像)：

public class MainActivity extends ActionBarActivity {

    @Bind(R.id.name)
    TextView name;

    public static final float DEFAULT_LAT = 40.440866f;
    public static final float DEFAULT_LON = -79.994085f;
    private static final float OFFSET = 0.1f;
    private static final Random RANDOM = new Random();


    public static float lastLatitude = DEFAULT_LAT;
    public static float lastLongitude = DEFAULT_LON;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
    }

    @OnClick(R.id.button)
    public void SayHi(Button button){

        BusProvider.getInstance().post(new LocationClearEvent());

        lastLatitude = DEFAULT_LAT;
        lastLongitude = DEFAULT_LON;
        BusProvider.getInstance().post(produceLocationEvent());

        button.setText("hi");
    }

    @OnClick(R.id.change)
    public void ChangeLocation(){
        lastLatitude += (RANDOM.nextFloat() * OFFSET *2) -OFFSET;
        lastLongitude += (RANDOM.nextFloat() * OFFSET *2) -OFFSET;
        BusProvider.getInstance().post(produceLocationEvent());
    }

    @OnClick(R.id.view)
    public void changeView() {
        Intent intent = new Intent(this,MainActivity2Activity.class);
        startActivity(intent);
    }

    @Override protected void onResume() {
        super.onResume();

        // Register ourselves so that we can provide the initial value.
        BusProvider.getInstance().register(this);
    }

    @Override protected void onPause() {
        super.onPause();


        // Always unregister when an object no longer should be on the bus.
        BusProvider.getInstance().unregister(this);
    }


    @Produce
    static public LocationChangedEvent produceLocationEvent() {
        // Provide an initial value for location based on the last known position.
        return new LocationChangedEvent(lastLatitude, lastLongitude);
    }

    @Subscribe
    public void listenLocation(LocationChangedEvent event){
        Log.i("main", event.toString());
    }

第二个Activity中这样写：

public class MainActivity2Activity extends ActionBarActivity {

    @Bind(R.id.location)
    TextView change;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_activity2);
        BusProvider.getInstance().register(this);
    }

    @Subscribe
    public void onLocationChanged2(LocationChangedEvent event){
        if(event == null) Log.i("null","event is null");
        Log.i("location change", event.toString());
        change.setText(event.toString());
    }


    @Override
    protected void onResume() {
        super.onResume();
        BusProvider.getInstance().register(this);
    }

    @Produce
    public LocationChangedEvent voichang(){
        LocationChangedEvent a = new LocationChangedEvent(1.1f,1.1f);
        return a;
    }

    @Override
    protected void onPause() {
        super.onPause();
        BusProvider.getInstance().unregister(this);
    }
}

LocationChangedEvent是这样的：

public class LocationChangedEvent {
    public final float lat;
    private final float lon;

    public LocationChangedEvent(float lat,float lon){
        this.lat = lat;
        this.lon = lon;
    }

    @Override
    public String toString(){
        return new StringBuilder("(")
                .append(lat)
                .append(",")
                .append(lon)
                .append(")")
                .toString();
    }
}

运行是这样的图：

单击第三个按钮绑定的是这个事件：

 @OnClick(R.id.view)
    public void changeView() {
        Intent intent = new Intent(this,MainActivity2Activity.class);
        startActivity(intent);
    }

跳过去，第二个Activity就崩溃了，出现了以下错误：

07-08 10:50:44.666  23212-23212/com.pp.kpm.test W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa6270288)
07-08 10:50:44.666  23212-23212/com.pp.kpm.test E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pathprint.kpm.test/com.pathprint.kpm.test.MainActivity2Activity}: java.lang.RuntimeException: Could not dispatch event: class com.pathprint.kpm.test.LocationChangedEvent to handler [EventHandler public void com.pathprint.kpm.test.MainActivity2Activity.onLocationChanged2(com.pathprint.kpm.test.LocationChangedEvent)]: null
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
            at android.app.ActivityThread.access$600(ActivityThread.java:130)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

网上搜了很多内容，都没有反映，不知道是哪里出问题了，请大家指导一下。