How to create and manipulate lineforces via code?

I'm trying to make an active ragdoll, and im using lineforces and attatchments to make him ball up, but the lineforces wont respond to my code, even when i had them physically placed into the ragdoll dummy's limbs. Heres my code:

lf1 = Instance.new("LineForce",bodyparts.LeftArm)
lf1.ReactionForceEnabled = true
lf1.InverseSquareLaw = true
lf1.Magnitude = 1250
lf1.MaxForce = 1000

lf2 = Instance.new("LineForce",bodyparts.RightArm)
lf2.ReactionForceEnabled = true
lf2.InverseSquareLaw = true
lf2.Magnitude = 1250
lf2.MaxForce = 1000

lf3 = Instance.new("LineForce",bodyparts.LeftLeg)
lf3.ReactionForceEnabled = false
lf3.InverseSquareLaw = false
lf3.Magnitude = 1250

lf4 = Instance.new("Lineforce",bodyparts.RightLeg)
lf4.ReactionForceEnabled = false
lf4.ReactionForceEnabled = false
lf4.Magnitude = 1250

function ballup()
    lf1.Attatchment0 = attatchments.LeftGrip
    lf1.Attatchment1 = attatchments.LeftFaceGrip

    lf2.Attatchment0 = attatchments.RightGrip
    lf2.Attatchment1 = attatchments.RightFaceGrip

    lf3.Attatchment0 = attatchments.LeftFoot
    lf3.Attatchment1 = attatchments.LeftAss

    lf4.Attatchment0 = attatchments.RightFoot
    lf4.Attatchment1 = attatchments.RightAss

wait(MaxHealth - Health)

    lf1.Attatchment0 = attatchments.LeftGrip
    lf1.Attatchment1 = nil

    lf2.Attatchment0 = attatchments.RightGrip
    lf2.Attatchment1 = nil

    lf3.Attatchment0 = attatchments.LeftFoot
    lf3.Attatchment1 = nil

    lf4.Attatchment0 = attatchments.RightFoot
    lf4.Attatchment1 = nil
end