使用RoboGuice @InjectFrament 时报错?报错

我在Activity里面使用RoboGuice的@InjectFragment来初始化我自定义的Fragment，但运行出错了，代码如下：

public class CrimeActivity extends RoboFragmentActivity {
    private static final String TAG = CrimeActivity.class.getSimpleName();

    @Inject FragmentManager fm;
    // 这里想声明并初始化自定义的Fragment
    @InjectFragment(R.id.fragmentContainer) private CrimeFragment fragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_crime);
        RoboGuice.getInjector(this).injectMembers(this);
        Log.i(TAG, "CrimeActivity onCreate...");
    }
}

报错信息如下：

java.lang.NullPointerException: Can't inject null value into class com.android.criminalintent.CrimeActivity.fragment when field is not @Nullable

哪位高手对RoboGuice比较熟悉的，求助！！！