RopeConstraint wont work with Character, why?

I made this rope swinging script, using rope constraints. But whenever I shoot the rope I get stuck midair, unable to move. I have no idea why. Any help please?

--// Variables

local players = game:GetService("Players") 
local plr = players.LocalPlayer

local char = plr.Character
local head = char:FindFirstChild("Head")

local athA = Instance.new("Attachment") 
local athPart = game.Workspace.AttachPart --This is a specific part that the rope attaches to
local athB = Instance.new("Attachment")
athB.Parent = athPart 
athA.Position = Vector3.new(0,0,-1)
athA.Parent = head
local length 
local uis = game:GetService("UserInputService")
isSwinging = false

--// Functions:

uis.InputBegan:Connect(function(key) 
    if key.KeyCode == Enum.KeyCode.R  then
        if isSwinging == false then
            isSwinging = true
            script.WebSound:Play()
            wait(0.1)
            rope = Instance.new("RopeConstraint")
            length = (head.Position - athPart.Position).magnitude
            rope.Attachment0 = athB
            rope.Attachment1 = athA
            rope.Length = length
            rope.Visible = true 
            rope.Parent = head
        --  I have tried adding a HumanoidStateType here
        end
    end
end)

uis.InputEnded:Connect(function(key)
    if key.KeyCode == Enum.KeyCode.R then
        if isSwinging == true then
            rope:Destroy()
            isSwinging = false
            --  I have tried adding a HumanoidStateType here
        end
    end
end)