'root' is not allowed to commit files, even using 'su'

[Bryan Batten]

Until recently, I've been able to log in as a normal user, use "su -l"
to become root, edit a file, then check it in using CVS. Now, I get
this message:

cvs [commit aborted]: 'root' is not allowed to commit files

The exact command that fails is:
-su(root)# cvs ci -F ~/tmp/ci.txt /etc/network/interfaces

I've tried adding a writers file in $CVSROOT/CVSROOT/writers with these
lines:
bryan
root

but the problem persists. Its acting like CVS can't find the original
user name.

Any help will be greatly appreciated.

Thanks,