Issue connecting to a data source after moving SSRS to a new server

I recently moved SSRS to a new server.  The migration went fairly well and most of the reports are running fine on the web server.  I've been going through each project to point the project  to the new report server location and then updating the connection string on shared data sources to again point to the new server.  Almost all of my data sources point to one of 2 catalogs (one for finances and one for fundraising) and I have successfully updated many of the projects without an issue for both catalogs.  However, I have a folder that uses both data sources.  I've made all the changes to point to the new server and when I test the connection string, it is successful.  However, if I try and run the query for the financial data source, it errors out with the following error (last paragraph).  If I turn on the old SSRS server, it works fine.  I've checked and double checked that everything points to the new server and it does.  Again, this data source is used in other projects and works fine there - just not in this one project.  I've even deleted and recreated the data source and it still won't work.  I can't figure out what the problem is... and feel the error is misleading.  

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)