Psst. Tab_OnClick event does not trigger when you click on a Tab in the Tab Control. You have to use the OnChange event of the Tab Control. But how do you refer to the current tab or active tab so that you can conditionally execute code?
No point looking at the MSDN article on the Tab Change Event.
Sample code is in an Access 2000 article: ACC2000: VBA Procedure to Determine Current Page of Tab Control
The current tab name is in TabCtrl.Value - oh, and you don't use the Page Name, you use the Page Index Number.