I've tried this spell various ways but nothing seems to work. I cast it and get a swirling green mist and nothing appears. Tried sleeping 24 hours, casting with both hands, one hand, inside, outside. No luck. Any tips?

Do you have any kind of perks for spell absorption? Because that tends to be the problem with summoning things.

Also, if you have the Atronach stone, it will do the same as what WHo iZ AsiaN stated

Black market is not cast with your hands.
Its a lesser power, meaning you activate it with the shout button.

This. You're definitely not casting it.

Ok I'll try that then. Funny that when I select it the aura shows up on my hand and I can cast it just nothing happens when I do. It's not really clear that it's a shout because of that. I don't have any of the spell absorption stuff. I'm casting Dremora Lords just fine. I'll just try the shout and hopefully that will do it.

It's working for me, I just used it when I became over encumbered in a dungeon. Wish He had more gold though.