Stephen
We have made some progress with this. A colleague has found that by including an xsd in the overall solution more than once, we have the problem, i.e. we effectively have xsd files with the same target namespace. Changing the namespace in copies of the file resolves the problem.
We did this deliberately to minimise the impact of change (or at least give us some flexibility of when things get released).
Specifically, we have a BaseDictionary.xsd that defines a number of common types. These are primarily simple types with restrictions, such as enumerations or regex validation. We shared (using sourcesafe) this dictionary into each schema project that we needed to use the base types, instead of referencing a base project, on the basis we could choose when to update the specific schema project if the base dictionary changes.
The schema projects used in the solution for this thread all use the base dictionary, so each of them have, effectively, their own copy of the basedictionary schema that has the same namespace. If the namespace is changed to be unique, the problem goes away.
So, we now know how to get the map to work, but we need to rethink our approach to the deployment side should things change.
Thanks for your help & suggestions.
Regards
Mark