I'm having a problem with my shout to summon Dunaviir not working. I try to execute the shout via voice cammand Dun Ai viir and the check mark appears but the dragon never shows up. I even disabled my kinect and tried the good ol fashioned hold down my RB but still nothing. Any suggestions.

I think the Durnheiver shout works like a conjuration spell, where you have to shout where there is enough space for him to form, since he comes out of the ground.

You have to be pointing your crosshair at the ground, not the sky.