Thanx very much for your quick and helpful reaction.
I am approaching slowly: When I try to follow your instruction:
"*create the plpgsql language in the dotlrn databases, than can be done issuing this commmand as root in your database server:
su - postgres -s /bin/sh -c "createlang plpgsql dotlrn",
then I get following error: "createlang: could not connect to database dotlrn: FATAL: database "dotlrn" does not exist"
Any help as always highly welcome
Mischa