Maybe, you have to set a skin first and create a mapping afterwards.
(Not every single step is logic, it is a bit about trial and error - although I use MED quite long.)
Did you import it in the Skin Editor?
Did you open the Skin Settings window?
did you choose in MED: View -> 3D View -> Texture & Gouraud?

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt