My stanhopea collection

[Yéri]

I'm agreeing with everything that has been said above, you seem to keep them too wet.

Keeping a plant "wet" should be kept in mind for the watering regime, but first think about your conditions (compared to the greenhouse you've bought it from for example).
If you have a colder greenhouse with less ventilation let's say, your watering regime should be less intensive, as the medium will take longer to dry out.

I hope this helped