Frenchman

I have a C5 2009 plate 1.6 hdi fitted with sat nav . The ice is a myway system. I cannot get it to play music from a sd card with wma or mp3 files on them. Tried a standard sd card and also a sd hc card. When the sd card with the maps on , the nav system works fine. Has anyone got this system playing music from a sd card working, if so how?? Thanks Steve