I make a rope, but it's intermittent

[NoIE]

code JointBall.lua for ropeRoot, rope2, rope3 ... :

Script.parentObj = nil--entity

function Script:Start()
   local center = self.entity:FindChild("center")
   if center~= nil then
    local pos = center:GetPosition(true)
    self.jointBall = Joint:Ball(pos.x, pos.y,pos.z,self.entity,self.parentObj)
   end
end

code Mass.lua for Sphere 1 :

Script.parentObj = nil--entity

function Script:Start()
   local center = self.entity:FindChild("center")
   if center~= nil then
    local pos = center:GetPosition(true)
   self.jointBall = Joint:Ball(pos.x, pos.y,pos.z,self.entity,self.parentObj)

   end
   self.timer = Time:GetCurrent() + 8000
end

function Script:Draw()
   if self.timer < Time:GetCurrent() then
   self.entity:SetMass(30)
   end
end

After 8 seconds, the sphere's weight is set to 30.

edit:

Screenshot with Skybox.