That's most likely because you've animated the movement only at one single frame. Now understanding animation basics there must be a transition between minimum 2 frames to make anything move. In this case first select the whole model and add keyframes for the first frame. Then go a bit ahead in the timeline and then start moving the part you want to be animated to a different position :)

i dont understand but thanks! :D

Watch Valve tutorials and you'll understand more

i did but it doesnt do shit