Model as Prefab - lots of this prefab causing problems

Hi there! I have a problem. I have made a Keypad/Keylock Model with GUI in WorldSpace and Script on it. I have made a prefab with this Gameobject/Model. If i use one of this prefab in the scene everything works fine. but if i use this prefab more than 1 time in the scene i get problems. because the second prefab is talking with the first prefab. if i press a button on the second prefab, the button get pressed on the first prefab and on the second prefab nothing happens! why is this so? i show you a pic of the inspector variables! ![alt text][1] [1]: /storage/temp/111033-pic3.jpg why is this so? thanks for help!