This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
That would mean, I think, that no ancestor of that element declares a namespace for which DbGML is the prefix. Look in your XML for namespace declarations. And make sure your parser is set up to be namespace-aware (although it probably is).
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com