I am working with mindfussion.diagramming diagram. i am facing a problem. i have design screen, in the design screen when I placed a control by selecting it and dragging it onto the diagram and as soon as I press right mouse button it throws the ob exception.

Exception as {System.NullReferenceException: Object reference not set to an instance of an object.
at MindFusion.Diagramming.Silverlight.InteractionState.Start()
at MindFusion.Diagramming.Silverlight.BehaviorBase.OnMouseMove(MouseEventArgs e)
at MindFusion.Diagramming.Silverlight.Diagram.x2c5d1da1234c3a6a(Object xe0292b9ed559da7d, MouseEventArgs xfbf34718e704c6bc)
at MS.Internal.CoreInvokeHandler.InvokeEventHandler(UInt32 typeIndex, Delegate handlerDelegate, Object sender, Object args)
at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, Int32 actualArgsTypeIndex, String eventName, UInt32 flags)}

some time there is no exception but when you click on shape node then raised exception.

I am also use diagram.canceldraw() method but it did not work.

Please suggest some way to solve this issue.
Thanks in advance.