animation.Play isn't working

private var zimGO: GameObject; //already found.

    else if(Input.GetKey(KeyCode.S)){			
rigidbody2D.velocity.y = (moveSpeed*-1) * Time.deltaTime;
    				rigidbody2D.velocity.x = 0;
    					zimGO.animation.Play("ZimDown");

Well I’ve look up plenty of things and nothing helps me. I make an animation out of sprites and put it in an animation folder in my assets. Then add the animation to my character. When i press ‘S’ it should play the animation, but it either says it needs to be legacy(if it is it doesn’t change anything) or it just doesn’t do anything.

or this one: