It's in the editor.. Why not in the game?!

Arrgh.. I've managed to successfully impliment several custom models into the Map Editor... BUT, when I try to play the game, it's no good, and they just show up as non-selectable shadows. What gives? I've already set the paths proper.. What can I do?

if ure useing milkshape your not allowed to add anything after you use the ZERO JOINTS TOOL that means no uv editing ,no addin models ,so adding bones, and espacialy mergins the groups together all that must be done before you apply the zero joints plugin other wise it stuffs up in game but will work in WE

if ure using 3ds max i dont know it might be something to do with your models materials .