Help animation error!

ok so i am making my weapon movements and i get this error

Assets/Walk.js(7,43): BCE0044: expecting :, found ‘;’.

function Update(){
 if(Input.GetKeyDown("z"))
   if(Input.GetKeyUp(";z"));{
 animation.Play("Walk", PlayMode.StopAll);{
 animation.Stop("Walk"));
 }
}

Your curly braces are a little messed up.

function Update(){
 if(Input.GetKeyDown("z"))
   animation.Play("Walk", PlayMode.StopAll);
 else
   animation.Stop("Walk"));
} 

You do not need to check if the button is released, just use else, if nothing is down it means it is up.