"The prefab you want to instantiate is null" what am I doing wrong nested...?

I have a game object that's created at runtime, I've attached a script to it after creating it, that script holds an instantiation of an object should something happen.... because this game object is created at runtime, and the script is attached after it's creation, I can't access the inspector to set the prefab...

So I'm trying to add it in code...

something like this: this script is attached to the object that's waiting for the condition to create the prefab:

var PS_top_ordered : GameObject;
PS_top_ordered = GetComponent("PS_top_Ordered");

And later, inside the update (){ is this:::

if (Input.GetKeyDown ("a")){

    Instantiate(PS_top_ordered, transform.position, transform.rotation);

}

The GetComponent function returns a component, not a prefab of a game object. Yet you assign it into PS_top_ordered which is a game object.

I can't even believe the Javascript compiler allows you to do that! Use C# :)