What is wrong with my EX2D code?

Hello all,

I'm new to programming and I'm attempting to create a game as a project to help me learn the ropes. I've purchased EX2D to help with my sprite animations. I'm getting the following error trying to animate a sprite:

 NullReferenceException: Object reference not set to an instance of an object
 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.GetProperty (System.Object target, System.String name)
 UnityScript.Lang.UnityRuntimeServices.GetProperty (System.Object target, System.String name)
 Char Move with Anim1.Update () (at Assets/Char Move with Anim1.js:23)

The following is my code:

 var xmovement : float = 0;
 var ymovement : float = 0;
 
 public function Start()
 
 {
 var spanim:exSpriteAnimation;
 var sprite:exSprite;
 
     sprite.spAnim = GetComponent.<exSpriteAnimation>();
 sprite.spAnim.Play("PlayerIdleAnimation");
 }
 
 
 public function Update()
 {
 var spanim:exSpriteAnimation;
 var sprite:exSprite;
 
 sprite.spAnim.Play("PlayerIdleAnimation");
 
 /*while(xmovement > 0)
  { 
  sprite.spanim.Play("PlayerWalkUpAnimation");
  }
 while(xmovement < 0)
  { 
  sprite.spanim.Play("PlayerWalkDownAnimation");
  }
 while(ymovement > 0)
  { 
  sprite.spanim.Play("PlayerWalkLeftAnimation");
  }
 while(ymovement < 0)
  { 
  sprite.spanim.Play("PlayerWalkRightAnimation");
  }*/
 }

The part towards the bottom is commented out because I'm trying to get the first part working properly before I implement the rest.

Any pointers or corrections / criticisms are much appreciated.

Thanks in advance!