SG in CR posted somewhere above that in the nature this plant is often exposed to direct sun. Also I saw some videos with plants in situ and they really grow on very small branches that are exposed to sun. Despite that my lamp is about 23 cm above the plant, the light there is comparable with the light of a lightly overcast day. It makes buds on the existing spikes, but they yellow and fall. I have some hope for the left bud, it is still green.