Referencing Rect in script C#

I am trying to write a script to display a tooltip, but I get this error… I cant use the inspector OnPointerEnter because I am using a drag and drop implementation, and one blocks the other… Any ideas what am i doing wrong?

NullReferenceException: Object
reference not set to an instance of an
object
UnityStandardAssets.Characters.FirstPerson.DragDrop.TooltipOn
() (at Assets/Scripts/DragDrop.cs:73)
UnityStandardAssets.Characters.FirstPerson.DragDrop.Update
() (at Assets/Scripts/DragDrop.cs:56)

This is my code…

private Rect currentRect;

void Start () {
currentRect = gameObject.GetComponent<RectTransform>().rect;
}

void Update(){
TooltipOn();
}

  public void TooltipOn()//if the mouse is over the icon draw tool tip
        {
            if (currentRect.Contains(Event.current.mousePosition))
            {
				Debug.Log("I am here");
            }
        }

http://docs.unity3d.com/ScriptReference/EventSystems.EventTrigger.OnPointerEnter.html

I found my soulution here… :DDDD