Richard,
Are you using the offical release version of 3.3.0.0, or one of the RC builds? A problem that we noticed in the 3.3 SymbolDesigner is that trying a load a symbol palette when the designer was editing a previous palette was causing this particular exception. Restarting the designer before loading the second palette helps avoid this condition. We hope to have this problem fixed in time for the minor update of Diagram that is coming up. Can you send this custom symbol palette over so that I can take a look at it? You can email it to ''
[email protected]'' with a reference to this forum posting.
Thanks,
Prakash Surendra
Syncfusion Inc.