Yes, this is the problem.
I sent an e-mail to palinkas about it and he suggested me to create a new edge routing, but this doesn't solve my problem.
I have created an edge routing inspired to the one proposed about Sugiyama (Orthogonal).
Unfortunately it is not what I need.
What I really need is the one that an edge starts from and ends to the same vertex and when I move this vertex, the loop-edge, follows the vertex in matter.
I would like to show this problem using images but unfortunately I can't post them in this forum.
I would like also to know where the edges are drawn so I can draw them by a routing made by my self.