Usually it means that there are new replies ou haven't read yet. It works somehow for me... But the 'Mark all posts as unread' function is buggy (at least, it is on my IkonBoard, didn't try it here...)
P.S. Choose a more precise topic title next time...
The site is marking topics as unread but I know that I have read them allready. Am I doing anything wrong. Does anyone else have this problem:confused: