In the output there always no error when the player die but it not changing team
game.Players.PlayerAdded:connect(function(plr)
plr.CharacterAdded:connect(function(char)
char:WaitForChild("Humanoid").Died:Connect(function()
plr.Team = game:GetService("Teams"):WaitForChild("Lobby")
end)
end)
end)

3 comments
Is the damage to kill the player being done on the client? Is the above code in a server script?
I've also try RemoteEvent to but nothing did'nt work at all! :(
This should be a server script. I cannot see anything wrong with this code make sure that the team exists or you will get an inf yield warning with WaitForChild