Problem in document saving

After customizing the Protoapp sample code. The links are not saving in the document. When we open it the link disappears Thats the problem (version is Godiagram 2.5.2 .NET 2.0). Problem is after customizing GraphNode class. im trying to inherit this class from GoGeneralNode. everything is fine. But when I customize it to create ports with no difference between left and right ports then the diagram is unable to save the links. the error is :-

if anyone want complete code mail me at
Error 1 'ProtoApp.GraphNode' does not contain a definition for 'InPort' D:\Documents and Settings\Administrator\Desktop\temp\ProtoApp\GraphDoc.cs 147 17 ProtoApp

The ProtoApp sample makes use of the GoSimpleNode class, not the GoGeneralNode class. Because GoSimpleNode only has two ports, available as the InPort and the OutPort properties, connecting a link to a GoSimpleNode has no ambiguity regarding which port to use.

Because GoGeneralNode can have many ports, and because you seem to want to have both source and destination links connected to any port, you will need to save identifying information for the particular port that each link is connected to. Then when loading the link, you will be able to find the proper port on the proper node, for both the FromPort and the ToPort of each link.
FlowCharter provides an example of this, since there are up to four ports on each node. It sets GoDocument.MaintainsPartID to true, so that it can save the PartID for each node and port, and then when loading can call set the PartID for each node and port. When loading the links it calls GoDocument.FindPart to find the desired port given the PartID.