Programmatically adding fragment to framelayout in android

I am trying to build a UI combining both static and dynamic elements. For this, I have divided my activity into fragments - all app navigation is then done by replacing fragments instead of navigating between activities. In my main activity layout, I am using a `FrameLayout`: ``` <FrameLayout android:id="@+id/mainframe" android:layout_height="match_parent" android:layout_width="match_parent" android:layout_below="@id/topsection" android:layout_above="@id/lowersection" /> ``` I have a fragment declared as such: ``` public class MyFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment return inflater.inflate(R.layout.fragmentlayout, container, false); } } ``` Then, in my main activity (which extends FragmentActivity and uses the import `android.support.v4.app.FragmentActivity`, I am attempting to load this fragment into the frame layout. ``` MyFragment myf = new MyFragment(); FragmentTransaction transaction = getFragmentManager().beginTransaction(); transaction.add(R.id.mainframe, myf); transaction.commit(); ``` I have followed this from many other examples, however I am receiving a compiler error on the `transaction.add()` command, which nobody else seems to have encountered. The error I am receiving is: `The method add(int, Fragment) in the type FragmentTransaction is not applicable for the arguments (int, MyFragment)`. Why is this? The `MyFragment` class extends `Fragment` so I would've thought this would work. What am I doing wrong? Edit: The imports for my main activity are: ``` import org.joda.time.DateTime; import android.app.FragmentTransaction; import android.database.Cursor; import android.os.Bundle; import android.os.Handler; import android.support.v4.app.FragmentActivity; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.TextView; import android.widget.Toast; ```