I'm having a hard time summoning dragons. I have both the Odahviing shout and the Durnehviir shout and even when in an open field I cannot get them to summon. I'm trying to call Odahviing to Dragonsreach now and I've been running all over the balcony trying to summon him with no results. Help?

I have all DLC content installed, if that makes any difference.