Hello Renee.

what does it mean when the error says 'data type mismatch, umbinding object objName'?

Just to expand a little bit on what Andy told you:

Obviously, you bind your combo and list boxes by setting the ControlSource property to the name of a field in a table, cursor, or view or to a form property. One gotcha! to be aware of is that you can only bind these controls to character, numeric, or null data sources. If you try to bind a combo or list box to a Date or DateTime field, Visual FoxPro will complain and display the following error at run time:

Error with -Value: Data Type Mismatch.
Unbinding object