When I copy a shape in my application and then attempt to paste it, I get the error shown in the attachment.

Transcribed:
The Paste transaction FailedRolledback
Error Log:
1. Paste failed on a single node: Object reference not set to an instance of an object.

Can someone give me hint for where to start looking for what I've done wrong?

Thanks,
Herb.

Most likely this is the problem. In order to solve it, make sure that your custom objects are deep cloneable (i.e. implement the ICloneable interface for them).