Android Question Marker on OSM map

I can't get a marker to show up. Please help.
Sub GPS_LocationChanged (Location1 As Location)
Dim bm_user As BitmapDrawable
bm_user.Initialize(LoadBitmap(File.DirAssets, "Pointer.jpg"))
'lblLat.Text = "Lat = " & Location1.ConvertToMinutes(Location1.Latitude)
'lblLon.Text = "Lon = " & Location1.ConvertToMinutes(Location1.Longitude)
'Msgbox(Location1.Latitude & " Lat " & Location1.Longitude & " long1", "Loc")
MapCenter.Initialize(Location1.Latitude, Location1.Longitude)

' mark.Initialize("title","descr",MapCenter.Latitude, MapCenter.Longitude,Null)
mark.Initialize("title","descr",Location1.Latitude, Location1.Longitude,bm_user)

ZoomLevel=25
MapView1.Zoom=ZoomLevel
MapView1.SetCenter3(MapCenter)