[Closed] CurveControl disappears from utility

I am having problems with a curveControl disappearing entirely from my scripted utility. A quick example:

run the following code, and open the script in the Utilities panel. You will see the curveControl. Now go to the Modify panel and then click back on the Utility panel, and the curveControl is gone and all internal data is undefined! I am on Max 2012 64-bit

utility Curve_Test "CurveControl tester"
 (
 		CurveControl Curve "curve control:"
 )