Please help on Miltassia buds drying out!

[taki1979]

Hello everyone!

I bought Miltassia Peggy Ruth in February. Grown-up, healthy one. Special orchid ground, watering once a week, T=21-23C.
No problems with the roots, neither with leafs. But I have a problem with its buds and absence of blooming.
First it gave two buds in June and both dried off. Second time in the mid of September it gave two arrows with two buds each and one of the buds already dried off. Others are still green and healthy but not blooming yet. You can see dried off bud on the foto.
Please advise what can I do to support blooming?

p.s. I didn't succeed to find info neither on russian forums, nor in this forum