Well, that's good that you at least remember to check the resistance. This is a *must do* in my opinion. What resistance is this coil you are having problems with reading at?
As for the unsatisfactory results? I'm not sure because there is a LOT of variance in how someone builds a coil for an RBA... two are unlikely to ever be *exactly* the same... but I doubt it has much to do with it just being 28 gauge wire. If in doubt source some new wire, maybe a lighter gauge like 30 and try that. Maybe there IS something wrong with that specific wire you have... You didn't tell us... have you built a coil using that exact same wire that worked well?
What are you using for wick?