I was porting some code from a prototype project into the production solution, and frankly it wasn’t going well! Debugging the Silverlight aspect I was seeing an AG_E_PARSER_BAD_TYPE error thrown when one of my view models was being loaded.

I knew it was something I had missed – at least that was something.

I was using Prism formerly the Composite Application Guidanceso the issue was caused when loading from my sub module.

To cut a long (well an hour at least) story short, you need to ensure that any references used by the module are also available to the shell. In my case I was referencing controls toolkit in the module, but hadn’t made sure this was referenced in the shell.

One to remember…