It would depend where you're calling the button from. If it's not throwing an error then you're referencing correctly. However, the click event of a page doesn't fire when you click the tab caption, it fires when you click inside the tab. Silly right? So that won't work. FYI, you place the button on the main form.
Basically, it scrolls down to (try to) display the full contents of your tab, so you would need to decrease the height of the subform within your tab if you want that behaviour to stop.