I contacted Freedomfest and this was their reply:
I looked into the code and did a test registration and it worked for me. This coupon code will only work for people trying to register as an attendee at the full price. So if they try to register as a young professional, professor, or student the code will not work since those roles are already deeply discounted. The code needs to be in all caps.
I can also add the code on the backend if they missed applying their coupon code at the beginning of the registration. I double checked the spelling on our end and we have VIGILANTE. Please let me know if you hear of any other issues or if I need to apply the coupon code on the back end for any of your followers and we will help to make sure the code is applied to their registration. I’m not sure if it was a spelling error, the caps lock, or the incorrect registration role that prevented the coupon from working. If this keeps happening and the correct role, spelling, and caps were used please let me know all the details so I can get the registration system to have IT work on it immediately.
Thanks Jeff, it's working. I think I had put young professional and since as you said it's already discounted then it wouldn't work since it doesn't stack.