Miltoniopsis not blooming

[hanzy08]

Hello everybody! I have a problem with miltoniopsis.. I can bloom phals, oncidiums, vandas and dendrobiums. I just can't seem to make my miltoniopsis orchids bloom. The new bulbs produce new growths instead of spikes.. I had them outside during the spring when it was a lot cooler and the growths developed faster but still no spikes.. I fertilize once a week with a bloom booster and kelpmax twice a month. The growths look fat and the leaves has nice grassy green to them with some red tinge that indicates it's getting enough light.. any tips or inputs?