Animated props not animating

Whenever I place animated props into my maps, such as the rotating metal chimney pieces that Coulee uses or the grandfather clock from Mann Manor, they don't animate in-game. I've set them to prop_dynamic instead of static and selected the animations I want in the model browser, but they don't move. What do I need to do to fix it?

Strange, I looked through all the available boxes several times before and never saw that one. It was what I needed though. Thanks!