problem setting up

Hi, I am just trying to build a duplicate of our database server.
Like the main one, I compiled it from source, ran initdb, created a
superuser, and then proceded to creating a database.
However, db creation is denied to the superuser. Likewise,
if I create the db as user postgres and then change ownership, I still
do not have enough rights to, say, install a language.
The pg_database.datdba as well as pg_user tables seem to have correct values.
Where could I look next?
Regards
Wolfgang Hamann