Show Last Known Location

Hi, i have a problem using your library.

I use the code proposed in the Android Guide to show GPS location in map. The problem is the following:

If i fix first the GPS position and then i start the application, the marker isn't shown until i re-fix the position in the emulator (if i wait for XX secs the marker is not shown neither).

Is any way to get the last known position in order to show the marker with this position instead to wait for the GPS update its position?

I have tried this but it doesn't work:

lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location l = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
WgsPoint wgs = new WgsPoint(l.getLongitude(), l.getLatitude());
marker.setLocation(wgs);

Thanks