Maybe you need to change the play speed because if it's animatng realy slow it can look like it's not animating.
Some animating tools put hundreds, even thousands, of tween (inbetween) frames so you have to place a crazy high speed to make it animate.
An example of this is "DBP/Media/Models/Gun/New Gun.X"
It's a rotating chain gun anim that only lasts a couple of seconds but it has 20160 frames, so thats around 10000fps play speed!!