Underwing to rear fuselage?

I’ve built a HC Hurricane, and I had trouble with the fabric covered portion of the underwing/rear fuselage joint. I didn’t expect to have trouble with my Hasegawa kit, but I am.

The gap always seems too big. I try to fill it and sand it, but I don’t really even come close to the proper look. I assume it is a technique issue.

Ideas?

QT

What doesn’t look right about it and what are you using to fill the gap?