I've been having problems with associtations. When I define an assocaition using a set markup, I get a casting error.

The iesa.ISet cannot be cast into any .net types.

I change my assocaition from an set to a bag and everything works.

None of the examples I have seen mention this. am I missing something in the use of the set.

Are you using the correct namespace for the ISet? The full name is Iesi.Collections.ISet. Also make sure your project has a reference to Iesi.dll. Lists and bags use the native .Net collection types, but since .Net doesn't have an ISet interface you need to reference another library (Iesi.dll) in order to use them.