cvs commit problem

[Joss, Werner 3936 S-RD-MP2]

Hi all,
I'm currently trying to get my cvs pserver running on redhat 7.2.
I've managed to get it working partly by setting up xinetd as described
in the faq-o-matic.
so far, I can connect to cvs, also checkout modules, but if I try to commit
changes, I get the following error:

cannot create_adm_p /tmp/cvs-serv13750/CVI/MDAQ
Permission denied
cvs commit: saving log message in /tmp/cvsiIyJXt

anyone knows what to do ?
(of course, /tmp is writeable by anyone on the server as well as the client
machine...)

thanks
Werner