[Inactive] Why does my keys not work when i try to "drop" the other one?

i have 2 Keycard and they have this script:

local KeyName = script.KeyName
local KeyColor = script.KeyColor
KeyName.Value = script.Parent.Parent.Name
local colorBlock = script.Parent.Parent.Clr
colorBlock.BrickColor = KeyColor.value

script.Parent.MouseClick:Connect(function(plr)
    local chr = plr.Character
    local key = script.Parent.Parent


    if chr:FindFirstChild(KeyName) then
        local oldKey = chr:FindFirstChild(KeyName)
        oldKey.Parent = workspace
        oldKey.WeldConstraint:Destroy()
        oldKey.CFrame = key.CFrame * CFrame.Angles(0,0,math.rad(15))
    end

    key.Parent = chr
    key.CFrame = chr.RightHand.CFrame * CFrame.Angles(math.rad(90),0,math.rad(180))

    local weld = Instance.new("WeldConstraint")
    weld.Parent = key
    weld.Part0 = key
    weld.Part1 = chr.RightHand
end)

Workspace: https://imgur.com/a/fWASchb

When you pick one up it does that fine but when you click another one it should drop the one you just picked up and then pick up the other one. idk why it doesnt work but it just doesnt.

Edit: Ive done everything on GnomeCode's tutorial or whatever it is. https://www.youtube.com/watch?v=s-zXAgU_sKA&t

Everything else works fine except the keys