Unless I missed something a shout does not call a dragon? It is just an attack. Aside from that, you are doing something I never did. I am the thane in Whiterun and another town, I bought 2 houses and I have Lydia staying in one to protect the stuff I leave there. I found a guy to hire for 500. He does magic, has a bow and uses a war ax. He has been fantastic for me. You could either just go with how the story is now playing out for you or start over? I started over 4 times.
How about that. I had no idea you could call a dragon! Maybe this will help you?
http://answers.yahoo.com/question/index?qid=20111112224329AAIUS5v
It looks you have to complete the main story before you can call one. Where did you find that shout at?