I have a form to convert an opportunity to an Active Program.  In order to convert it, the user must assign the Company with the Prime Contract and the associated Charge Code.  I already have a close button, but I need to make it where they get an error message saying they must assign the Prime and Charge Code prior to closing the form.  I'm certain there is already a video on this.  Can somebody point me in the right direction.  The main table behind the form is tbl_Tasks and that table contains the field for Company_ID (Prime) and ChargeCode_ID.