created a subform using a form I had previously created as the 3rd page of a tab control. Looks good in design, but when I try to save it I get an error message. "This expression is typed incorrectly, or it is too complex to be evaluated. For example, a numeric expression may contain too many complicated elements. Try simplifying the expression by assigning parts of the expression to variables." Well as far as I know I don't have any expression. Is this related to the subform or is it something else? The tab contol just shows a big white blank in the form.

Any hints?

Are you trying to use a control as a subform? You must use a form. The third page of a tab control is still part of that tab control. Maybe I'm mixed up here, but I suggest that you make sure your subform is an actual form rather than a control. Then let me know if you still have problems.

I inserted a page in the tab control and then placed the subform (using a form I created from a separate mini-table) onto that page.