Go4Expert - Add tooltip on BMP file

How can i add tooltip in my image file (*.BMP).I meant whenever my mouse cursor comes to the image file ,a tooltip should be displayed.Below

Code:

le.Format("DADC\nName:%s latitude: %d",objFlightParam.m_strEntId,fLat,);

        m_objToolTipCtrl.AddTool(this,le,0,IDB_BITMAP5);

IDB_BITMAP5 is ID of the bitmap .
It is showing a debug assertion error.
Is there any other way