When I select a value in a list, it disappears or gives me an error message.

You may have specified the wrong column in the BoundColumn (forms and reports) or the ListBoundField (data access pages) property box. The BoundColumn or ListBoundField property determines which column's data is stored in the field that is specified in the ControlSource property box. For example, if you have a combo box on a form or report that has a SupplierID column and a SupplierName column, the bound column would be the SupplierID column (the foreign key field) even if the SupplierName column is the only visible column.