Fall through model (bridge)

[Yen]

I cant stand on the bridge. After importing the model and went into game mode, the avatar just falls through the model. Any ideas?

[Ricky]

Is the model solid white or whatever material on it?

[Yen]

The first time i imported it, there was no problems but later somehow i just cant walk on it anymore. There are materials applied but not on all of the faces. I tried exporting the same model and then import the model into crysis and again i cant walk on it.