Phal problem - the buds are drying out

[heathenpride]

Hey guys,

I got the following problem:
I bought a new phal about three weeks ago and didn't water it because the soil seemed to be pretty moist and I didn't want to exaggerate with the water now that it's cold...

This phal has two flower branches, and the un-opened buds on the blooming one have started to get dry and reddish.
I thought it was something to do with me not watering it so I gave it a few glasses of lukewarm water.

But the problem persists, and also some buds have been dried out on the non-blooming branch, although the problem is more severe on the blooming branch.

I must note that the flowers are OK, i.e. not withered.

Maybe the blooming branch does not have sufficient resources of some kind (water, light) to maintain additional buds as the branch is already pretty heavily occupied with bloom?
Maybe it's lack of humidity?
I'm also using some artificial light (40 W) above the flowers, maybe it can cause the buds to dry?

What am I doing wrong? I feel really bad!