Whenever I try to summon my Dremora Lord in a dungeon or inside, he wont appear. The purple portal to oblivion appears and the sound and animation occurs, minus Valkynaz. This is annoying because when I try to conjure him for a distraction or to assist me in battle, he's never there when i most need him. Anyone else had this problem?

Jeez, that must svck. Does it work when you're outside?

Seems to... sometimes once I'm dead I can hear him cursing the enamies, like he spawned on my death!
Oh, and true sig - yeah, Lydia annoys the crap out of me, and why she has to live in my house with my wife is beyond me

I tried to see if I could get the spell to mess up on purpose. No joy. I did notice that sometimes the Dremora Lord would appear in close by but different parts of the dungeon. In one there was a secret chamber to my right and he kept portalling in there. For the most part it worked fine, I could not replicate your results, sorry.