Clint is right. The pruning is your problem. Nikko Blue should never be pruned for at least 5 years and you get to know which limbs are really dead. In zone 6 we get a warm up and some frost which kills the buds. When I am not lazy I cover my bush and keep it covered until May when there is no threat of frost and I get a lot of flowers those years.
It took my Nikko almost 4 years to bloom. I ordered it from an online vendor and it was a little thing. If you keep pruning you will never see a bloom. It looks dead but those buds come from what looks like brown stems. I had my bush in deep shade and it bloomed every year if we did not get a late frost.
