Can somebody help me fix this error, C0 is not a valid member of attachment? Please Help?

Hello, since the new Player Model is running (R15)... i don't have idea about how to change Shoulders CFrame without errors, so can anybody help me?

I'm trying to convert a R6 Script in R15 script.

Before

RArmJoint = Character.Torso:FindFirstChild("Right Shoulder")
LArmJoint = Character.Torso:FindFirstChild("Left Shoulder")
RHipJoint = Character.Torso:FindFirstChild("Right Hip")
LHipJoint = Character.Torso:FindFirstChild("Left Hip")

After

RArmJoint = Character.UpperTorso:FindFirstChild("RightShoulderRigAttachment")
LArmJoint = Character.UpperTorso:FindFirstChild("LeftShoulderRigAttachment")
RHipJoint = Character.UpperTorso:FindFirstChild("RightCollarAttachment")
LHipJoint = Character.UpperTorso:FindFirstChild("LeftCollarAttachment")

But, when i start the game, i got errors.

-- C0 is not a valid member of Atachment

C0 Codes

while true do
    wait()
    Twist = (Twist * 31 + TwistConvergence) / 32
    Tilt = (Tilt * 31 + TiltConvergence) / 32
    Speed = (Speed * 15 + SpeedConvergence) / 16
    if Character.UpperTorso.Velocity.y < MinVelocity and not Character.Humanoid.Sit then
        Character.Animate.Disabled = true
        VMag = math.sqrt(Character.UpperTorso.Velocity.magnitude / 48)
        DMag = ((Character.UpperTorso.CFrame * CFrame.Angles(1.57, 0, 0)).lookVector - Character.UpperTorso.Velocity.unit).magnitude
        MinVelocity = -50
        HasReset = false
        Character.Humanoid.PlatformStand = true
        Raise = math.max(math.min(Character.UpperTorso.Velocity.y / 800 - (DMag * VMag / 4), 1), -1)
        ChangeWeld(RArmJoint,
            CFrame.new(1.5, 0.5, 0) * CFrame.Angles(Raise, (math.random() * 0.2 - 0.1) * Raise, 2.355 / Speed - 1.57 - Twist / 1.5),
            CFrame.new(0, 0.5, 0))
        ChangeWeld(LArmJoint, 
            CFrame.new(-1.5, 0.5, 0) * CFrame.Angles(Raise, (math.random() * 0.2 - 0.1) * Raise, -2.355 / Speed + 1.57 - Twist / 1.5),
            CFrame.new(0, 0.5, 0))
        ChangeWeld(RHipJoint,
            CFrame.new(0.5, -1, 0) * CFrame.Angles(Raise, (math.random() * 0.2 - 0.1) * Raise, 1.046 / Speed - 0.698 - Twist / 1.5),
            CFrame.new(0, 1, 0))
        ChangeWeld(LHipJoint,
            CFrame.new(-0.5, -1, 0) * CFrame.Angles(Raise, (math.random() * 0.2 - 0.1) * Raise, -1.046 / Speed + 0.698 - Twist / 1.5),
            CFrame.new(0, 1, 0))
        CurrentCameraLV = (game.Workspace.CurrentCamera.CoordinateFrame.lookVector * Flat).unit
        Character.UpperTorso.CFrame = CFrame.new(Character.UpperTorso.Position, Character.UpperTorso.Position + ((Character.UpperTorso.CFrame * CFrame.Angles(1.57, 0, 0)).lookVector * Flat * 15 + CurrentCameraLV)/16) * CFrame.Angles(-Tilt - 1.57, Twist, 0)
        Character.UpperTorso.Velocity = Character.UpperTorso.Velocity*SD + CurrentCameraLV*Tilt*5 + Vector3.new(-CurrentCameraLV.z, 0, CurrentCameraLV.x)*Twist*5
        Character.UpperTorso.RotVelocity = Vector3.new(0, 0, 0)
    elseif not HasReset then
        Character.Animate.Disabled = false
        MinVelocity = -100
        Character.Humanoid.PlatformStand = false
        RArmJoint.C0 = CFrame.new(1.5, 0.5, 0) * CFrame.Angles(0, math.pi/2, 0)
        RArmJoint.C1 = CFrame.new(0, 0.5, 0) * CFrame.Angles(0, math.pi/2, 0)
        LArmJoint.C0 = CFrame.new(-1.5, 0.5, 0) * CFrame.Angles(0, -math.pi/2, 0)
        LArmJoint.C1 = CFrame.new(0, 0.5, 0) * CFrame.Angles(0, -math.pi/2, 0)
        RHipJoint.C0 = CFrame.new(0.5, -1, 0) * CFrame.Angles(0, math.pi/2, 0)
        RHipJoint.C1 = CFrame.new(0, 1, 0) * CFrame.Angles(0, math.pi/2, 0)
        LHipJoint.C0 = CFrame.new(-0.5, -1, 0) * CFrame.Angles(0, -math.pi/2, 0)
        LHipJoint.C1 = CFrame.new(0, 1, 0) * CFrame.Angles(0, -math.pi/2, 0)
        HasReset = true
    end
end

Please, help me!