Do you have the following defined as your userid field within your .cfg file?

# Auth user field. This is the field position in the database used for storing
# the userid who owns the record. Set to -1 if not used.
$auth_user_field = 0;

I noticed in your links your not including the name of the db file. Such as:

http://epona.tainted-butterfly.com/database/db.cgi?signup=1

should be:

http://epona.tainted-butterfly.com/database/db.cgi?db=default&signup=1

Unoffical DBMan FAQ

http://creativecomputingweb.com/dbman/index.shtml/