Problem with SqlServerCe

I have installed VS 2010 and VS 2012. VS 2012 uses SqlServer CE 3.5 and VS 2012 uses SqlServer CE 4.0.

The problem is that when a project uses a 3.5 file it tries to open it with 4.0 even if the app.config says to use the 3.5 provider.

Does anyone know how to fix this? The version of the assembly is pulled right out of the GAC. I uninstalled 4.0 and the reference auto updated its version to 3.5.1. However after installing 4.0 again it changes to 4.0. The error I am getting is that 4.0 cannot open a 3.5 file....they changed the file format from 3.5 to 4.0 and they are not compatible.

How can I connect to a SQL Server Compact 3.5 file as a data source in Visual Studio 2012?

The above link says it is NOT possible.

Tim S.

Using it as a data source in VS is far different than attempting to open it via API calls. It is possible to open it b/c it works on other systems. I am not sure why it isn't working on mine.