[Krx17]

You forgot the braces. { & }

pawn Code:

public OnPlayerStreamIn(playerid, forplayerid)
{
    if(IsVehicleAirBorne( GetVehicleModel( GetPlayerVehicleID( playerid ) ) ) )
    {
        new string[40];
        PlayerPlaySound(playerid, 1056, 0.0, 0.0, 10.0);
        format(string, sizeof(string), "Player %d is now streamed in for you.", playerid);
        SendClientMessage(forplayerid, 0xFFFFFFFF, string);
        return 1;
    }
}