what are you using to check your salinity? a refrac or a hydrometer? api are ok, sometimes, but they have a tendency to crap out when you need em the most, id suggest heading to an LFS, i prefer rosecity and seahorse personally, although davey jones locker is good too, and let them test your water for you.
also, a cycle can last up to 2 months for a saltwater tank, its rare, but not totally unheard of, my original cycle when i first set up my 20 long was 5 weeks before everything evened out to where it was supposed to be, and that was using 12 y/o live rock from an established tank that never dried out