Instantiate not working through window

Tried posting in answers but it wouldn't let me. So here goes...
Okay I'm trying to get an object to Instantiate. I have all the prefabs set up properly. Basically I want a window to pop up and allow the player to build a unit. Only I get this error:

NullReferenceException: Object reference not set to an instance of an object


if (dockGuiOn == true)//will check if true
{
// Register the window. Notice the 3rd parameter
windowRect = GUI.Window (0, windowRect, dockWindow, "Dock Menu");
}
}
//Make the contents of the dock window above
function dockWindow (windowID : int)
{
GUI.BringWindowToFront(windowID);
GUI.FocusWindow(windowID);

//build rigs as construct location
if(GUI.Button (Rect(30,20,55,16), "Build Rig"))
{
print("Hit Build Rig");
var drillShipRig : Transform;
drillShipRig = Instantiate (drillShipRig, transform.position, transform.rotation);
}
GUI.Button (Rect(15,40,90,16), "Bid on Contract");
GUI.Button (Rect(25,60,75,16), "Hire Workers");
GUI.Button (Rect(25,80,73,16), "Upgrade Rig");
GUI.Button (Rect(25,100,70,16), "Stack Rig");
GUI.Button (Rect(10,120,100,16), "Cold Stack Rig");

if(GUI.Button (Rect(1,1,16,16), closeTexture))
dockGuiOn = false;;
}


The part that isn't working is the section

if(GUI.Button (Rect(30,20,55,16), "Build Rig"))
{
print("Hit Build Rig");
var drillShipRig : Transform;
drillShipRig = Instantiate (drillShipRig, transform.position, transform.rotation);

Sorry if the formatting is horrible but I can't figure out how to get the tags to work properly. I've used this in other programs but can't figure it out for the life of me. Any help is greatly appreciated.

 

Which line is that error referring to? That'll tell you which of the objects is null, and that'll tell you where to look for the cause.

Also, with extra spaces added so it'll show:

Code (csharp):

1. [ code ]
2. ...
3. [ /code ]

 

Nevermind folks! Figured it out!!!!