I ahve created a sub form with 3 combo boxes to look for various data in some tables. They are only used to search and not update or edit. However, when I tested main form with the subform embodied none of the combo boxes on the subform work. However if I open the subform independently everything works as it should.

Has anyone come across this problem before and how do I fix it.

Thanks for any help that you can give.

What immediately comes to mind is to consider your main form. How is it linked to your subform? If your main form drives the subform, then only records associated with that appearing on the main form would be displayed. This is the reason that it works fine alone. Personally, I am no guru but I would consider making the subform the Main Form and vice versa. Then, base the new subform (Old Main Form) off of a query that considers the parameters displayed on the new Main Form. (Old subform) I hope that is not confusing. I feel like I am talking in circles here! But, in short, see how the two forms are linked and you may come upon your own realization.

You need to include the main form in any references ie:MainFormName!SubformName.Form!MyControl use the expression builder to obtain the correct references if setting query criteria.
HTH