As I understand you, you have a tab control with each tab having a subform. One of these subforms does not show up in Form View, but in Design view, correct?
Everything shows up in Design View, so it is normal that you see the subform there. It can have various reasons you are not seeing the subform in form view though:
- Please check if the subform control is on top (or on the tab control) of the tab control
- Make sure you set visible = true in the subform Users properties
- Make sure that DisplayWhen = "Always" or "Screen" and not "Print"
(Also take care that you set these properties for the subform in question and nothing else, it can sometimes be a hassle working with tab controls. You can check that you are working on the correct properties by looking on the selector drop down above the properties)