How to set CVS be the reserved checkout mode only?

[LIU,SHI-ZHOU (HP-China,ex2)]

Hi there,

CVS server version:1.11.2 on HP-UX 11i
CVS client: Win CVS 1.3.8.1 on Win2K

How to set CVS be the reserved checkout mode only?  I mean that if one
checkout a file and edit it, before he/she commit it, other can't edit the
file.

Now, we use the rcslock.pl file according to the book: Version Management
with CVS for CVS 1.11.2 by Per Cederqvist et al
And run the command  "cvs admin -l", but thus make no one can commit any
file.
If i run the command "cvs admin -L", when one editing a file, other also
want to edit the file, it will give out the message:

 "cvs server: cannot write /export/Repo/smftp/testlock/CVS/fileattr:
Permission denied"

but thus also can't prevent him to edit the file and then commit it. what
should I do now?

Thanks & Best Regards,

Joe Liu  (Liu ShiZhou)
Software Engineer
HP China Software Solutions Center
Tel: 86-21-28982089 
Fax: 28982112    T/N: 279-2089