I did get the authorization to reply correctly.. I hope the following part doesn't contain spoilers (imvho it doesn't):
If not all of the parameters are correct, an error message is displayed. If you supply just one wrong parameter, it still gives an error message. When all parameters are supplied correctly, it is silent, indicating success - then, when returning to the previous page (with 1 wrong parameter), silence yet again. So that seems to work.
However, the message area blatantly disagrees.
At least now we can be stuck together ;]