Per 
Ellied's Sandbox & Associated Thingies
OH GOD NESTED TABS
Okay.
So.
I think all you have to do is:
1. ensure that the deepest level of tabs inside your first outermost tab contains the same number of tabs as the number of outermost tabs.
2. switch the names of all of the the outermost tabs and all of the innermost tabs in the first outermost tab, except for the first tab in each of those categories
3. assuming any of that made sense, the rest should be smooth sailing. If that didn't make sense, look at the source code for this page at your own risk.
4. please make sure you have at least 3 sanity before looking at the source code for this page.