A Question about Multiplayer Game

[zrj]

I made a sever in the multiplayer game,then my friends join.
Then I choose the Axis,select an airport,so,at the right of the screen shows the aricraft.
Then I click the button "CREAT",but then it`s return to the screen of the list of the aircrafts instead of start the game.
Why?
PS:When I join a server which is searched automaticlly,I can start the game after I clicked CREAT.