User can not more login

Hello *,

I am searching for a weired error... Since all users are working fine,
I was now root and done a 'su - postgresql' to create a new user with

createuser --password devel.debian
Shall the new user be allowed to create databases? (y/n) n
Shall the new user be allowed to create more new users? (y/n) n
Password:
CREATE USER

Now the weired thing is, that the new user is visible in

/home/postgresql/data/global/1260

but not in

/home/postgresql/data/global/pg_pwd

All other users are there...
Here I have the striped output of

SELECT * FROM pg_shadow ORDER BY usename;
usename | usesysid | usecreatedb | usesuper | usecatupd | passwd | valuntil | useconfig
------------------+----------+-------------+----------+-----------+-------------------------------------+----------+-----------
devel.debian | 107 | f | f | f | | |
michelle.konzack | 100 | t | t | t | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
omegasector | 103 | f | t | t | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
peer.janssen | 102 | f | f | f | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
pmc.omega | 105 | f | t | t | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
root | 104 | f | f | f | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
postgres | 1 | t | t | t | | |
tamay.dogan | 101 | t | t | t | mdXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX | |
(9 rows)

Hmm, it does not create the password, even if it had ask me for it...
And if I continue with

createdb --encoding=utf-8 --owner=devel.debian devel.debian
CREATE DATABASE

and the I use 'psql -l'

List of databases
Name | Owner | Encoding
------------------+------------------+-----------
devel.debian | devel.debian | UNICODE
michelle.konzack | michelle.konzack | SQL_ASCII
omegasector | omegasector | UNICODE
peer.janssen | peer.janssen | UNICODE
root | root | SQL_ASCII
systemdb | root | SQL_ASCII
template0 | postgres | SQL_ASCII
template1 | postgres | SQL_ASCII
(9 rows)

In endeffect, if I try to login as $USER devel.debian with

psql devel.debian
Password:
psql: FATAL: Password authentication failed for user "devel.debian"

How can this happen?
There is no difference between the user "debian.devel" or
"michelle.konzack" or any others...

It was realy weired, since I create the databases automaticaly from a
script while I create new SYSTEM users... Now it fails.

The used database is

psql (PostgreSQL) 7.4.7

contains support for command-line editing

Greetings
Michelle Konzack

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