Visio vsd file connecting lines problem
 

I have imported a Visio vsd file into OmniGraffle Pro 5.0.2 and the connecting lines are superimposed on top of and meet in the centre of each shape.

Is there any way, without having to drag each line to the edges of the shape, to get each connecting line to snap back to the edges of a shape?

I'd appreciate any suggestions for overcoming this problem.