There could be several things. Did you set a $db_key field? Have you changed the number of fields since you first added a record? Those are the first two things that come to mind
If you'd like me to take a look at your .cfg file, copy it to a web-accessible directory (one where you would place .html files) and rename it to default_cfg.txt. Then come back here and tell me where I can pick it up.
JPD
http://www.jpdeni.com/dbman/