animation doesn't work???

I recorded an animation of my weapon attacking, and it would play when the left mouse is pressed. now the animation worked, but it kept playing by itself even i checked off "Play Automatically". what is happening? i did initialized it though. my code:

 #pragma strict
 
 var thedamage : int = 50;
 var Distance : float;
 var MaxDistance : float = 1.5;
 public var TheHammer : Transform;
 
 function Update () 
 {   if (Input.GetButtonDown("Fire1"));
     {
         TheHammer.animation.Play("attack");
         var hit : RaycastHit;
         if (Physics.Raycast (transform.position, transform.TransformDirection(Vector3.forward), hit))
         {
             Distance = hit.distance;
             if (Distance < MaxDistance)
             {    
                 hit.transform.SendMessage("ApplyDamage", thedamage, SendMessageOptions.DontRequireReceiver);
             }
         }
     }
     if (TheHammer.animation.isPlaying == false)
     {
         TheHammer.animation.CrossFade("HammerIdle");
     }
 }