Habmin2 not storing items

When I create a Diagram in habmin 2 and name and save it, it doesn’t appear on the left side. Is this correct?
So I can see it when created it, but on the next entry of habmin2 it is gone. When I click on Diagramms then, I get an error:
can’t open List (Fehler beim öffnen der Liste). It seems, habmin can’t save anything, but it does’nt tell on saving, but on reloading.
What do I have to change?