"The deal url is invalid" - what does this mean?

I'm trying to give feedback through the iTrade system, and I get the message that the deal url is invalid. It's a thread in the Buy, Sell or Trade > Services section, and of course the thread works fine, it's the one I cut and pasted from the address bar, so there's no typos at work here.

Am I only allowed to give iTrade feedback to the thread starter? That's the only thing I can think of that might have caused this message, because I was trying to give feedback to someone whose message appears further down the thread. Any ideas what is going on?

 

Yes, feedback can only go between the thread starter and any of the other posters.

 

Thanks Tops, that was what I suspected.