cvs [export aborted]: cannot export into a working directory

[Stephan Feder]

Hello,

exporting part of a repository with

        cvs -d :fork:/repository export -Dnow module/submodule

fails (same with :ext:) with server message

        cvs [export aborted]: cannot export into a working directory

but 

        cvs -d :local:/repository export -Dnow module/submodule

succeeds (client/server 1.11 on Linux).

I am using a separate LockDir and TopLevelAdmin=yes in config, and
access to certain top level subdirectories of the lock directory and the
repository is restricted by group rights, but other cvs commands do not
take offense.

Anyone any idea?

Regards
        Stephan