Cannot save “multiple inboxes” settings in GMail

Question

I just tried to setup multiple inboxes as described in this Google video.

Unfortunately I notice that the "Save changes" ("Änderungen speichern") button is greyed out!

Maybe my filter-rule is wrong? I took a screenshot of the example setting that I tried:

I know that before I once had "multiple inboxes" in use, so I'm really confused as to why I suddenly cannot setup those anymore. As the tab shows up, the labs feature is obviously activated.

Answer 1

After you make the change, go to the 'General' tab and click 'Save' there.

http://productforums.google.com/forum/#!topic/gmail/rI-p7UPB4N8

Answer 2

You cannot use "Priority Inbox" and "Multiple Inboxes" at the same time! You have to change from "Important first" to "Classic(al)" in either the little drop-down arrow on the right side of your "Inbox" or in the dropdown in the "Inbox" tab in "Settings".

Solution first found here and here on Google Groups.