Downloaded maps won't go past ''Start Game'' -1 reply

Hi. This is my first time downloading something for Warcraft so I could be doing something completely stupid, but I hope you can help resolve this frustration for me. I have downloaded a map, with a mission and all in it. I followed the installation instructions, yet when I go to play it, I click ''Start Game'', all the info scrolls up like normal, but then it just comes back and I can't play. Any help? :bawl:

Download the latest patch.