All I can say is keep trying! I hit the refresh button on my wait screen, it send me to the ticketmaster europe generic site. Then i hit the back, and reload it came up with a different page and finally redirected me back to the main start up screen, i just entered my code again and it went through. Just got 2 london GA.
Seems very inconsistent...but it is possible to enter the code again after a first failed attemt and get through!
hope this helps
cheers
andrew