So I've unlocked all three of Durnehviir's words but no matter where i shout or the distance I can not get it to work. I know you are supposed to shout at the ground so that's not the problem and I've tried different locations and still no luck! I've watched youtube vids and did it the same way they did still nothing! Can somebody please hep me?

Just aim at the ground in a fairly wide-open area and hold down the button to say all three words.

I had the same issue when I first aquired this shout, then I realized you must make sure you have enough space for to spawn a dragon, and make sure you hold the shout (RB) until he spawns.
I hope this helps.

Wonderful! I was not holding down (RB) long enough I was just tapping it. Thank you for the help. I don't think i would have figured out that you have to hold it down longer. Kinda hits me as a low blow it was something so simple. Thank you again!