Why team shown in GUI is not my team?

Hello.

I'm new to Roblox, so excuse me if this question is stupid, but I didn't find anything in wiki.

I've created 2 teams "Mafias" and "Policemen". For now, I assign all players to mafias team. But in-game, every player gets Policemen team, I don't know why.

My code:

local mafiaTeam = nil
local policeTeam = nil

function onPlayerAdded(player)
    player.Neutral = false
    player.TeamColor = mafiaTeam.TeamColor -- set to mafia  
end

function setUp()
    mafiaTeam = Instance.new("Team", Game:GetService("Teams"))
    mafiaTeam.Name = "Mafias"
    mafiaTeam.TeamColor = BrickColor.Red()
    policeTeam = Instance.new("Team", Game:GetService("Teams"))
    policeTeam.Name = "Policemen"
    policeTeam.TeamColor = BrickColor.Blue()
end

setUp()
Game.Players.PlayerAdded:connect(onPlayerAdded)

What's the problem? If you can figure it out, help me please.

Thanks in advance

UPDATE: as it seems to be, the problem is with GUI. Physically, I'm in mafias team (I've checked player's properties with server console + my name color is red, as it should be if I'm in mafias team), but GUI shows that I'm in policemen team. Any suggestions?