I have two PtToggleButtons

PtToggleButtonA
PtToggleButtonB

I wrote code to clear the screen and I am using this code to unset the toggle buttons.

PtSetResource(pWidget, Pt_ARG_FLAGS, Pt_FALSE, Pt_SET);

This works as I expect when the two toggle buttons are not part of a group.  

I then made the two toggle buttons part of a group so that I could set them to be mutually exclusive.

Now, when my application launches, neither button is selected.  (As expected)
When the user selects one button, it deselects the other (As expected)
However, when my code runs to clear the screen (deselect both buttons) it no longer works.

What am I missing?

Any help is appreciated.  Thanks.