key triggered animations scripts problem

i have some problems... if i make an animation to an object and give it to the object the object ofcrs preforms the animation...

but if i make a GetKeyDown("w") script and add it to the object and start the game nothing happends...

i have tried some alot of different scripts and also tried to follow tutorials but the results gets the same...

sometimes with some scripts the game goes back to scene mode instead of start the animation...

Why is this happening? is there some sort of setting i have to make? or what sould i do?

MANY TY IN ADVANCE!