Adding Sequence Flow to BPMN2 Editor

I am developing BPMN2 Editor using GEF. I have BPMN2 EMF Mo开发者_如何学Cdels. When I add SequcenFlow to My Editor it creates fine,But after that I cant able to any more BPMN Shapes in GEF Editor. I got Exception in IndexOutOfBoundsException in that processing getContentPane().add(child, index).

Why are you using getContentPane()? your children should be added to the model which is then read by the framework. Can you post some code?