Rect.Contains not working correctly

That's my code:

 void OnGUI (){
         if (GUI.Button(Rect1, "Rect1")){
             Debug.Log("Clicked the button with an image");
         }
     }


 
     void Update () {
         Rect1 = new Rect (
             button1.GetComponent<RectTransform>().position.x - (0.5f * button1.GetComponent<RectTransform>().localScale.x * 100f),
             Screen.height - button1.GetComponent<RectTransform>().position.y - (0.5f * button1.GetComponent<RectTransform>().localScale.y * 100f),
             button1.GetComponent<RectTransform>().localScale.x * 100f,
             button1.GetComponent<RectTransform>().localScale.y * 100f);
         
         if (Rect1.Contains (Input.mousePosition)) {
             Press1 = true;
             print ("inside");
 }
 }

Although my mouse is over the guibutton it's not detected and nothing is printed :( Please help me