Animation Not playing? (Noob)

My animation is not playing and I'm using this script on my guns so It can get mixed up so I decided to do variables so the animations didn't get mixed But I do get this error:

 MissingMethodException: UnityEngine.AnimationClip.Play
 Boo.Lang.Runtime.DynamicDispatching.MethodDispatcherFactory.ProduceExtensionDispatcher ()
 Boo.Lang.Runtime.DynamicDispatching.MethodDispatcherFactory.Create ()
 Boo.Lang.Runtime.RuntimeServices.DoCreateMethodDispatcher (System.Object target, System.Type targetType, System.String name, System.Object[] args)
 Boo.Lang.Runtime.RuntimeServices.CreateMethodDispatcher (System.Object target, System.String name, System.Object[] args)
 Boo.Lang.Runtime.RuntimeServices+<Invoke>c__AnonStorey15.<>m__9 ()
 Boo.Lang.Runtime.DynamicDispatching.DispatcherCache.Get (Boo.Lang.Runtime.DynamicDispatching.DispatcherKey key, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
 Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.String cacheKeyName, System.Type[] cacheKeyTypes, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
 Boo.Lang.Runtime.RuntimeServices.GetDispatcher (System.Object target, System.Object[] args, System.String cacheKeyName, Boo.Lang.Runtime.DynamicDispatching.DispatcherFactory factory)
 Boo.Lang.Runtime.RuntimeServices.Invoke (System.Object target, System.String name, System.Object[] args)
 UnityScript.Lang.UnityRuntimeServices.Invoke (System.Object target, System.String name, System.Object[] args, System.Type scriptBaseType)
 Animations.Update () (at Assets/skripts/Animations.js:7)

And I'm using this simple code:

 var Aim : AnimationClip;
 var Idle : AnimationClip;
 var Run : AnimationClip;
 function Update(){ 
 if(Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.W))
 
 Run.Play();
 
 else if(Input.GetMouseButton(1))
 
 Aim.Play(); 
 
 else
 Idle.Play();
 }

How can I fix this? Sorry for my simple question. I'm pretty much a noob in these things.