Mary
Right now we are guessing because we really do not have all the info. "We" probably know a dozen ways or more to do what you want, but we need specifics to provide you with specific information.
We need to know the name of the table or tables and associated fields that are also involved.
We also need to know the name of the control objects (text boxes, combo boxes) on the form that have anything to do with what you are attempting. If there is more than one form used, we need to know the names of each form.
We also need to know the ControlSource for these same objects.
Lastly, it would be helpful to now the RowSource and bound column info for any combo or list boxes that are involved.
I suspect the error is caused by a syntax error or a typo.
And just in case you do not know how to find the name of a control object on the form, open the form in Design mode. Make sure you have the Properties window open. (From the menu, "View" -> "Properties")
Click on a text box, list box or combo box that you want to identify. Now select the "Other" tab in the "Properties" window, and note the value in the "Name" field -- this is the name of the control on the form. (By the way, you can change the name to a more menaingful name on the form -- this really helps when writing code, or defining sort order. When a control is created with the form wizard, it will default to the name of the ControlSource. If the object is created manually, then Access uses its own naming convention, Text02, Combo04, etc)
Now to get the name of the ControlSource, RowSource and BoundColumn, click on the "Data" tab in the property window.
Richard