Distance-/springjoint

When i start the scence the distance between the chain parts is perfect.
After a few seconds it’s incorrect(too large) but thought by using the distance joint the distance is fixed…see my screenshots

link text still does not work for me:/

Thanks in advance!!

This probably won’t help, but maybe look at the Shadow Project from Unity. They not only demonstrate good lighting, but also, to a degree, rope physics. If you downloaded it, maybe you could utilize that to your advantage.