FATAL 1: SetUserId: user 'postgresql' is not in 'pg_shadow'

Hello,

I hope you can solve my problem I'm working on for 1 day now.

I did "pg_passwd passwd" and entered postgresql
I succeed to "initdb - u postgresql"
--
When I try to create a
postgresql@xxxx:/usr/lib/postgresql/bin$ createuser postgresql
Connection to database 'template1' failed.
FATAL 1:  SetUserId: user 'postgresql' is not in 'pg_shadow'

createuser: database access failed.
----

I also tried psql
postgresql@xxxx:/usr/lib/postgresql/bin$ psql -e template1 -c "CREATE USER
post
gresql"
Connection to database 'template1' failed.
FATAL 1:  SetUserId: user 'postgresql' is not in 'pg_shadow'
--
I'm running on the same machin as postmaster and changed the pg_hba.conf so
that it can trust everybody
when I look in my pg_shadow file I see : °  °Y ÃB

$¿postgresql



`Å.~
and I've a template1 directory
Any ideas? How do I access the database?

I also tried as root but same result : FATAL 1:  SetUserId: user 'root' is
not in 'pg_shadow'
and of course "psql template1" give the same error.
I'm using debian.

Best regards,
Anthony Goubard