I have an application that I have built in vfp3.0 which has no errors when compiling the program. However, when I run the application everything is great until I make a menu selection and then I get a FATAL ERROR! Unknown member App_Nbr. Please try again.

App_Nbr does not have a control source selected for it, since it is a textbox that is filled in from a set of choices the user makes in an adjacent Combobox. What am I doing wrong? Any ideas.
Thanks Rick