Permission error on restored discussion.

I've restored a deleted discussion from a backup, using phpMyAdmin, but when I try to view it I get
You don't have permission to do that.
I can view the discussion on my local install.
The discussion is in the forum database, and none of its attributes seem different to any other discussion.
I haven't had this problem before, and have been able to restore other discussions and comments without any issues.
Anyone know where I can look to see what the problem is?
Tagged:
0
Answers
OK - found the problem.
I had reordered my Categories, so the restored discussion had a Category ID which no longer existed.