I'm not trying to be moralizing or anything, you do what you feel is best, but I'd recommend expanding your horizons by writing about something completely unfamiliar - and I also recommend that you avoid berating your own ability to do research by saying "I'm not able". We're all able of doing what we want, we just need to work a bit for it. And you do most certainly not have to be an expert; not doing something because you're not an expert is like saying that you're afraid of failing; you're basically avoiding the most ultimate teacher of all: Failure and mistakes! ;)
But like I said, I won't berate you for this misunderstanding; it's been cleared now and all conversations feature misunderstandings, and it's mot always one or the other's fault; communication is intrinsically flawed that way.
Just thought I'd let you know that it can be misunderstood quite easily even though you never intended for it that way and tried to point it out ;)