It is obvious now, that Pakistan was interested in and seriously talking to Russia about the S400, but India cut Pakistan off by purchasing the same system in far larger numbers than Pakistan could and having a no sale clause to Pakistan as part of the sale agreement. Hence then the "interest" in the HQ9/FD2000 platform.
A shame, but it shows that the buying power of India will affect the growth of Pakistan-Russian military relations, and it will at times come down to binary decisions between India and Pakistan on a number of areas.