Hi Jen. I just tried this and it worked for me. Can you see if you missed any of these steps?
1. Go to the Customize tab. Click on the Tables/Fields tab link.
2. For the Customer table click on the Edit Fields...
3. Add a new field that has a Field Type of Text and a Size of 4000 characters. Called it TagList.
4. Customize your scren. In the list of fields in the Add Fields tab on the left you should now see a field called TagList. Add this to the screen.
For #4 you need to add the field TagList. Adding a textbox from the Add Objects tab and naming it "TagList" will not work.