how to make prefab clone as a child of prefab clone?

Okay I have browsed half of the internet trying to solve this simply issue. Im trying to make already cloned prefab instantiate another prefab clone and the instantiated clone as a child of the clone that instantiated it.

 var lazor : Transform;
 ...
     if(Input.GetAxis("shoot")){
         object = Instantiate(lazor, transform.position, Quaternion.Euler(0, 0, 180));
         object.parent = transform;
 ...
 }

This code was in a prefab. When I instantiate the object, everything is ok, but when I add the line "object.parent = transform" it disappears even from the hierarchy. (it doesn't even appear in hierarchy but appears then when I use yield WaitForSeconds.)

Tell me if you need more explanation. Thanks!