BUG Says "Job Blocked", nothing in the way

[vaffel]

I have had an issue many times where they fail to wash floors or take away food tray Because the job is blocked. but there is nothing that is blocking. Is this is a bug or am I just really dumb? anyway, I have taken a picture of a typical problem http://bildr.no/view/cGVNNlRS

and sorry for the bad english