I'm trying to trap the dragon at Dragons reach but when i use the "call Dragon shout (i just learned at the throat of the world ) he doesn't come.

Any one know what to do?

You need to do the full shout (all three words) so you need to hold down the shout key instead of just pressing it.

I don't know what to do because, I haven't encountered this problem. This also is the wrong forum for this post. This belongs in SPOILERS.

You have to talk to Balgruf or whatever his name is first, when him and his housecarl accompany you outside, they should prompt you to call the dragon, then it will work.

Next time, http://www.gamesas.com/index.php?/forum/178-skyrim-cheats-hints-and-spoilers/ is your place for things. Also, keep in mind you need to be in the place where the trap is located to successfully get the dragon there.

I'd suggest talking to the Jarl, it's possible you've missed some dialogue where he confirms the trap is set.

Turn your volume up all the way. The louder the shout the better chance he has to hear you.