GUI.DrawTextureWithTexCoords question


Can somebody please explain me how to use the rect for the GUI.DrawTextureWithTexCoords function?

I had this mini program:

public var rect :Rect;

public void OnGUI(){
    GUI.DrawTextureWithTexCoords(Rect(20,20,rect.width,rect.height), TX, rect);

Why does this not work? It shows nothing of my image

Argument one is screen position to draw into.

texCoords (argument 3) is a 0 to 1 range of what part of the image to draw.