I racked my head ... sth, but didn't ... sense of it

Hi,

If I have for example a file for a preparation for a multiple choice test and there are questions and answers, and one of the questions as well as the answer to it doesn't make sense to me, however I really tried to understand it, can I say "I racked my head over this question as well as it's answer, but didn't catch a sense of it"? I doubt especially about the preposition "over" in this case.
By the way, are there any differences between "rack one's head" and "puzzle one's head"? Are there any other alternatives? It would be great if you also mention what English they are more commonly used, American or British one.
Yeah, and of course I doubt that a native speaker would really say "catch sense", but hopefully you understand what I mean and could suggest me a more natural alternative.

Thank you