Tool Tip Priority Tag doesn't work

Hi, sorry for stressing again, but I need to present the new forum next week I'm stll having a lot of trouble. There are three different priority levels (default, I haven't change anything), the tool tip just works for two ("Normal" = blue, "Kritisch" = red). Mouse over at the grey one (should say "Niedrig" doesn't work, no matter what Browser I use (see screenshot). Link is for example:

http://www.forum.akgsoftware.de/index.php/forum-akg/categories/vestra/strasse?start=14

Could you please help me here?

Thanks!