Either

Hey guys! This is Mari from Germany. :)

Yesterday I took a test in my advanced English class and we had to translate a sentence that started with the phrase "Glaubst du nicht auch, dass...?"

I wrote: "Don't you also think that...?" which sounded good to me, to be honest.

My teacher told me it was wrong - in her opinion it's "Don't you think either that....?" Now I am a little bit confused, because in my opinion "either" doesn't really fit there... I tried to google this phrase and no one really uses "either" in this context.

Now I'd love to know whether there's a rule when it comes to "either". Because I can't tell my teacher "Well, I used google and only one kid on myspace wrote it like that."

Thank you so much!