Beginner gun script, 4.0 woe, assistance sought

The problem is not the script,the script works fine the problem is that in unity 4.0 the function
animation.Play("walking")
isnt working i dont know what to do for that so if someone knows plz help me because have stuck at this problem for almost 3 months and i can do nothing!!

here is the script if anyone knows hot to make the animation to play in unity 4.0 plz help me

 var Clips : int = 20; 
 var Range : float = 900; 
 var Force : float = 900; 
 var BulletsInClip : int = 27; 
 var RelodeTime : float = 4; 
 var BulletsLeft : int = 0; 
 var ShootTimer : float = 0; 
 var ShootCooler : float =0.9; 
 var RelodingAudio : AudioClip; 
 var ShootingAudio : AudioClip;
 var ShootingAnimation : Animation;
 var ReloadingAnimation : Animation;
 var ReloadingString : String;
 var ShootingString : String;
 
 
 function Start () 
 { 
     BulletsLeft = BulletsInClip; 
 } 
 
 function Update () 
 { 
     if (ShootTimer > 0) 
     {
         ShootTimer -= Time.deltaTime; 
     } 
 
     if (ShootTimer < 0) 
     {
         ShootTimer = 0; 
     } 
 
     if (Input.GetMouseButton(0)&& BulletsLeft > 0) 
     {
         if(BulletsLeft == 0) 
         {
             Relode(); 
         } 
 
         if (ShootTimer == 0) 
         {
             Shooter(); 
             ShootTimer = ShootCooler; 
         }
     }
 
     if (Input.GetKeyDown(KeyCode.R))
     { 
         Relode(); 
     }  
 }
 
 
 
 function Shooter () 
 {
     ShootingAnimation.Play(ShootingString);
     var Hit : RaycastHit; 
     var DirectionRay = transform.TransformDirection(Vector3.forward); 
     if(Physics.Raycast(transform.position, DirectionRay,Hit,Range)) 
     { 
 
         if (Hit.rigidbody) 
         { 
             Hit.rigidbody.AddForceAtPosition(DirectionRay* Force, Hit.point); 
         } 
     } 
     BulletsLeft --; 
     PlayShootAudio(); 
     if(BulletsLeft < 0) 
     { 
         BullletsLeft =0; 
     } 

     if(BulletsLeft == 0) 
     { 
         Relode(); 
     } 
 } 
 
 function Relode () 
 { 
     PlayRelodeAudio(); 
     ReloadingAnimation.Play(ReloadingString);
     yield WaitForSeconds(RelodeTime); 

     if(Clips > 0) 
     {
         BulletsLeft = BulletsInClip; Clips --; 
     } 
 } 
 
 function PlayShootAudio () 
 {
     audio.PlayOneShot(ShootingAudio); 
 }
 
 function PlayRelodeAudio () 
 {
     audio.PlayOneShot(RelodingAudio); 
 }