New growth purple then dies

[markbudde]

Hi all. I have a Neofinetia falcata in my terrarium, and it isn't doing very well. The problem is that the new growth starts out purple and then turns brown and dries up. Here's a pic of it.

It hasn't put out new roots in ages. Here's the conditions...
Mounted in a terrarium, near 100% humidity all the time. Day highs of 82.5, night lows of 72. Misted with RO about once a day. Fertilized rarely. Most of the roots are exposed, not wrapped in moss.
So why does the new growth start out purple?
1) humidity to high?
2) not enough fertilizer?
3) too hot?
Has anyone else had this problem?
-mark