Canon iP90 Printer Problem. My canon iP90 is not printing the black ink. I have tried everything

Question

My canon iP90 is not printing the black ink. I have tried everything and don't know what else to do.
I've changed cartridges about 6 times, I've cleaned, I've deep cleaned, I do the test prints and sure enough - everytime it's only the color ink, no black
I don't know what else to do?

thanks