Some strains smell stronger than others... and some strains, believe it or not.. have virtually NO smell at all.
Also, man.. your only in week #4 correct?
Give it time man..
I've said this time and time and time and time again... You have GOT to be patient when growing cannabis. Otherwise your wasting your time man..
be patient my friend.. you'll be rewarded greatly if you do.
Hell, you might have a low odor strain.. or like I said, only being in week #4 of flowering, the plants terpenes haven't really even began to really develop yet. The terpenes are responsible for the taste and smell of the plant/buds. Terpenes won't be fully developed and matured until the plant is fully ripe and ready for harvesting. If you don't smell anything by harvest time, then you just happened to get a low-odor strain... which is no big deal.
good luck.