Visualization Blues

One odd limitation in my visualizations: I don't seem to be able to work the dimmer switch. Lately my refuge tree, towards the edges, is almost black: dark, dark leaves flutter against the sky. And while sometimes Vajradhara is a brilliant, radiant dark blue, as he's supposed to be (and yes, that's a hard one to pull off in the first place) sometimes he goes a dim navy blue and sometimes he lightens to a cheery but not properly awe-inspiring sky blue. All this, so far as I can tell, completely unsteerable by my will. I can be willing Vajradhara to go a darker blue with all the concentration I can muster, and there he'll sit, untroubled -- pure sky blue.

I don't know if this is a good thing or a bad thing, but since it doesn't seem to be under my control at all, it just has to be whatever it is, I guess. Slightly unnerving.