How do I make the player play the walk animation when Z Elevation changes?

So I'm trying to make the player play the walking animation whenever the player is pressing W, S, Up arrow key, or down arrow key (this would change the player's Z elevation) I tried this but it would refuse to play the rest of the animation. Why does this happen?

Do you have it set to play walk on 'is moving' because the player isn't moving. If it's set only on key press, do you have another animation set to play when you press up and down, like jump or crouch?

And do you have an idle animation when the character is not moving?

Yes.

Ok so the problem is it's trying to play idle and walk at the same time. You'll have to add conditions to your idle animation that certain keys are not down.

Ooh that's how you do it... ;-;

Thanks. :)