Database Software

Hi
using credentials sseems to be easy, but I have problems using them in 11.2 on linux:
This code is running without any problems:
begin
dbms_scheduler.create_job (job_name=>'TESTJOB',job_type=>'EXECUTABLE',job_action=> '/tmp/mytouch.sh',enabled=>TRUE);
end;
/
In externaljobs.ora run_user is tomtester and rungroup tomtester as well.
so I this my problems seems no to be a protection problem.

For using credentials I have an OS user tomtester with tomtester as password. I can connect with the user and can execute /tmp/mytouch.sh without any problems.

So I created a credential:

begin
dbms_scheduler.create_credential('MYCREDENTIAL','tomtester','tomtester');
end;
/

And modify my job creation script to use this credential:

begin
dbms_scheduler.create_job (job_name=>'TESTJOB',job_type=>'EXECUTABLE',job_action=> '/tmp/mytouch.sh',enabled=>TRUE,credential_name=>'MYCREDENTIAL');
end;
/
This job fails with error# 27370
"EXTERNAL_LOG_ID="job_81737_5706",
ORA-27369: Job vom Typ EXECUTABLE nicht erfolgreich mit Exit-Code: Argument list too long
STANDARD_ERROR="Launching external job failed: Invalid username or password""

Invalid user or password - why that? None of my OS users can execute any job. The error message is always Invalid user or password.
Any ideas?
Thanks in advance
Joe