[Ironboy500[TW]]

1)

Код:

//when a player joins a team
if( gTeamCount[ ID_OF_TEAM ] == 10 ) //change ID_OF_TEAM with the actual ID of the team
{
    SendClientMessage( playerid, 0xFF0000FF, "There are already max players in this team, chose another one!" );
    return 0;
}
else
{
    return gTeamCount[ ID_OF_TEAM ]++;
}

You forgot on return 0;