When I use a RUC/GUC and am waitlisted, I make a point to call back multiple times to verify with multiple people that the RUC/GUC has been properly coded in the system. By doing it multiple times, my intent is that if it is not coded properly, one of those folks will spot the problem. Additionally, it is important to notice that when properly coded, a phantom/duplicate segment is shown in your itinerary where you cannot select a seat because it is showing you on the wait list. If that phantom segment does not show on-line, your RUC/GUC has likely not been properly coded onto your itinerary.