Copy sometimes works

Friday afternoon, my manager pointed out to me that Copy & Paste no longer work in my application.

Needless to say, I've been focused on that ever since. Ctrl-Drag & Drop still work for copying nodes. When I tried the serialization example from the User Manual, if found several classes that weren't serializable. The biggest problem was Pen. Eventually I got the binary serialization/deserialization to work.
Now Copy & Paste (calling GoView.EditCopy() and GoView.EditPaste() works sometimes and not others. I'm kind of stuck now. Any suggestions are appreciated.

More info. In place of calling EditPaste() I added the following code:

if (Clipboard.ContainsData(goView1.Document.DataFormat))
IDataObject c = Clipboard.GetDataObject();
System.Diagnostics.Debug.WriteLine("Data formats present");
foreach (string format in c.GetFormats())
// System.Drawing.Bitmap
// Bitmap
// Northwoods.Go.GoDocument
// System.String
// UnicodeText
// Text
objCopy = c.GetData(typeof(GoDocument));
There's more code to do someothing with objCopy if its not null, but objCopy was null and no exceptions where logged to the trace listener.
Maybe I should just serialize the copies of my business objects, put them in the clipboard and deserialize them on the Paste side add them to the diagram the same way I do when I load them from the database.

Thanks for the help, in advance.
P.S. - Chomping at the bit a WPF version of GoDiagram!

Have you tried to do the binary serialization test on the whole document in the cases where it is now failing?

The binary serialization test worked on the whole document I was having problems with, but failed on another, more complex document. Once I fixed that problem, the copy & paste worked. Thanks.