Why does this block for welding work on only one player?

    part = Instance.new("Part", workspace)
    weld = Instance.new("Weld", part)
    weld.Part0 = part
    weld.Part1 = workspace[playername]["Torso"]

I have tried using multiple different weld scripts to try to make this work but it only works with my player in studio and not in the game, and it does not work for anyone else in the studio, i can confirm playername is not a nil variable.

game.Players.PlayerAdded:connect(function(player)
    local leaderstats = Instance.new("Model") 
    leaderstats.Name = "leaderstats"
    leaderstats.Parent = player

    local money = Instance.new("IntValue")
    money.Name = "Money"
    money.Value = 0
    money.Parent = leaderstats

    local grass = Instance.new("IntValue")
    grass.Name = "Grass"
    grass.Value = 0
    grass.Parent = leaderstats

    local playername = player.Name
    game.Workspace.superimportantstuff.Player.Value = (playername)

    part = Instance.new("Part", workspace)
    weld = Instance.new("Weld", part)
    weld.Part0 = part
    weld.Part1 = workspace[playername]["Torso"]

    local Lawnmower1 = game.ReplicatedStorage.Lawnmower1:Clone()
    --Lawnmower1.Parent = player.BackPack
    --Lawnmower1.Parent = player.StarterGear
end)