SupportMapFragment - cannot cast from Fragment to MapFragment

Trying to put together a little MapFragment in an activity I'm building, but am having some trouble getting it all to work. I know that the Maps api and Play services are both installed correctly, as I did the test tutorial and everything worked fine.

Following the documentation here, I'm running into the following problem: In my setUpMapIfNeeded method, I can either use getFragmentManager() or getSupportFragmentManager(). When I use the getFragmentManager(), Eclipse is cool with it but when I run, I get a NoSuchMethodError saying that the method is undefined. When I opt for getSupportFragmentManager(), Eclipse doesn't like it and gives me the error "Cannot cast from Fragment to MapFragment". So what's the deal? Any suggestions?

private void setUpMapIfNeeded() {
    //Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        mMap = ((MapFragment) getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
        if (mMap != null) {
            //do things to the map
            mMap.addMarker(new MarkerOptions().position(LOCATION).title(EXTRA_URL));
            mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(LOCATION,15));
            mMap.getUiSettings().setZoomControlsEnabled(false);
        }
    }
}

Let me know if there's any other code I can provide and I'll be happy to post it quickly.