Healthy Dryadella edwallii won't bloom

[dlewan]

Below please find a picture (slightly out of focus - sorry) of my Dryadella edwallii and Pleurothallis niveoglobula. I got them both from Andy's Orchids at the same time. I think they're doing well; the new growths are strong and they get enough light that the leaves show pigment. The P. niveoglobula doesn't just grow but blooms. One tiny flower is visible in the picture. It actually had 6 flowers when I took the picture.

The D. edwallii, however, hasn't bloomed for me. I'm on a window sill, S-SW facing. Daytime temperature can get to 25°C. (24° is common.) Nights are a little cooler at ~20°. Humidity is consistently around 50%. The distribution map at POWO (vague as it is) suggests to me that the temperature ought to be reasonable.

Any help? Is there something obvious that I'm missing?

Thanks.