AI FPS tutorial collision problem

Im following the fps tutorial and im up to part 3 but i can't get my ai to collide with the ground it just falls

straight through, what could be the problem? it happens once i add the AIanimation.js code to it before I

added that it just hovered were i put it and didn't do any thing

PLZ help

-seatthief-

it sounds like you need to add a box collider to the ai so that it doesn't fall through the ground and also resize the collider to tightly fit the ai