qmail pop3 AUTH-ERR

Hello !
I have installed qmail on the linux-firewall IPCOP (see
www.ipcop.org). I have installed xinetd. I have tested the
/bin/checkpassword programm manually as descibed on the qmail webpage.
It works fine. But if I test it with telnet on port 110 in connection
with xinetd I get the message:

-ERR authorization failed

My xinetd.conf is:

service smtp
{
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no
        server          = /var/qmail/bin/tcp-env
        server_args     = /var/qmail/bin/qmail-smtpd Maildir
        #disable         = no
}
service pop3
{
        socket_type     = stream
        protocol        = tcp
        user            = qmaild
        wait            = no
        server          = /var/qmail/bin/qmail-popup
        server_args     = intern.eproduction.ch /bin/checkpassword
/var/qmail/bin/qmail-pop3d Maildir
#        disable         = no
}


I have also tried:

        server_args     = qmail-popup intern.eproduction.ch
/bin/checkpassword




Do you have any ideas in wich cases the ERR-Message comes
(checkpassword works, I am pretty shure)

Thank you very much

Greetings, Romeo