[imp] Context Manu is missing some entries.

[adam at lewicki.at]

Hi folks,

I have a strange problem regarding my IMP installation. In Dynamic mode some entries seem to be missing from the context menu when I right-click on a message. I can't mark messages as seen (or flag them) http://i.imgur.com/bEk46Xv
The menu entry is missing. 
On a different (plesk-based) installation of Horde everything is in place. See http://i.imgur.com/cjmdlN6

I don't think there is a config option I could set to regain those menus. 

Can anyone nudge me into the right direction as to what to do?

Best wishes
Adam