[development] Ahah sometimes working, different users

I'm doing my first AHAH coding. I have a "SELECT" in a form that is doing Ahah on event=change. For now, the returning code simply puts the selected value into a string and displays it in the wrapper. When I log in as the admin user, it works fine. When I log in as another user, the value of the select is not coming across in the POST from the ahah script. ie: the code runs and I see the result, but the result is an empty string because the is no $_REQUEST['field-name'] set. Has anyone seen this? -Matt