No, I think your doing it correctly if you get that message. Roku-channels.com is not "scrubbing" their list as many codes are invalid, broken, etc.
I recommend trying a few of the other code websites that are listed in the groups links as they are updated frequently. The group's database is also a good source for private channels.
Just in case: The below link would add private channel BBC to your Roku account.
--- In RokuDigitalVideoPlayer@yahoogroups.com, "fowlwasz" <fowlwasz@...> wrote:
> I've been trying to add channels found on http://www.roku-channels.com/, but every time I get a note saying the Channel Doesn't Exist. No doubt I am doing something dumb. Any ideas?