ActivateCell.FormulaR1C1 = "='" & MainPage.Name & "'!R10C22"

MainPage refers to the worksheet (code name) as you requested, and the
".Name" part is the property that returns the tab name (what the user
sees at the bottom of the worksheet). Be sure to include single quotes
around the sheet name, in case the sheet name has spaces in it. (Note
the single quote to the right of the second "=" and just to the left of
the "!".)
--
Regards,
Bill Renaud