In one of my games I have a script to add Stuff to the player, but with Trails, nothing happens, and there is no error. Here is the code:
--LocalScript
game:GetService('Players').PlayerAdded:connect(function(player)
player.CharacterAdded:connect(function(character)
character:WaitForChild("Humanoid").Died:connect(function()
wait(6)
local Trail = Instance.new("Trail")
Trail.Texture = ("rbxassesid://891390006")
Trail.Parent = player.Character["Right Arm"]
Trail.Attachment0 = player.Character["Right Arm"].RightShoulderAttachment --Error
Trail.Lifetime = 5
Trail.LightEmission = 1
Trail.Parent = player.Character["Right Arm"]
Trail.MinLength = 2
local Trail = Instance.new("Trail")
Trail.Texture = ("rbxassesid://891390006")
Trail.Parent = player.Character["Left Arm"]
Trail.Attachment0 = player.Character["Left Arm"].LeftShoulderAttachment --Error
Trail.Lifetime = 5
Trail.LightEmission = 1
Trail.Parent = player.Character["Left Arm"]
Trail.MinLength = 2
end)
end)
end)
game.Players.PlayerAdded:connect(function(player)
while not player.Character do wait() end
local Trail = Instance.new("Trail")
Trail.Texture = ("rbxassesid://891390006")
Trail.Parent = player.Character["Left Arm"]
Trail.Attachment0 = player.Character["Left Arm"].LeftShoulderAttachment --Error
Trail.Lifetime = 5
Trail.LightEmission = 1
Trail.Parent = player.Character["Left Arm"]
Trail.MinLength = 2
local Trail = Instance.new("Trail")
Trail.Texture = ("rbxassesid://891390006")
Trail.Parent = player.Character["Right Arm"]
Trail.Attachment0 = player.Character["Right Arm"].RightShoulderAttachment --Error
Trail.Lifetime = 5
Trail.LightEmission = 1
Trail.Parent = player.Character["Right Arm"]
Trail.MinLength = 2
end)

4 comments
Why are you using multiple PlayerAdded functions? Put it all into 1 of them. Also, make sure it's in a LocalScript. You must attatch it to an attatchment (ClassName: Attatchment) , it can't be a Part of any kind.
I tried it, but it still didn't work. Nothing happens, and there is no error.
Here is the new code: game:GetService('Players').PlayerAdded:connect(function(player) player.CharacterAdded:connect(function(character) character:WaitForChild("Humanoid").Died:connect(function() wait(6) local Trail = Instance.new("Trail") Trail.Texture = ("rbxassesid://891390006") Trail.Parent = player.Character["Right Arm"] Trail.Attachment0 = play
I put the edit in the question.