Help Dynamic attachment

[Caduceus]

Hello

I have next rope:

   

Here is Settings of rope:



Here is settings of Balls:



I want to drag a rope using red ball and yellow ball. Rope must NOT changing a length.

But result is so:

   

   

What I doing wrong?

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Sorry for big images.

I research what in your Chain demo you setup Phase on end point of chain to zero.
I put 0 for Phase in my rope end points and this is particullary help.

But there are still distance if I drag end of rope. Look:

   

How I can create hard link between attachment and rope?