Help with Soyo 53H and Riva TNT

[MikroMak]

I've got an old Soyo 53H with a Riva TNT AGP card. When I put in the TNT I can't get any video out. When I use an old Matrox PCI card I have It works fine.. I've tried my GeForce2 MX AGP in there and it works fine. No help on the soyo site accept that my cards not seated properly (gf2 worked fine though and the tnt works fine in other comps) ... ideas? anyone? help... the matrox card sucks..