The only thing I can think of is to make sure the column name you entered is correct (case sensitive). You could also try testing that SQL statement in phpMyAdmin to make sure it returns the expected result.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.