I am using SSRS 2008 R2 and Report Builder 3.0. I set up a shared data source via the browser (http://myserver/reports/) wherein the "credentials are stored securely in the report server" to use with multiple reports. Testing the connection via the browser works.
Now, I fire up Report Builder 3.0. I start a new report and "Add Data Source". I select the "Use a shared connection", browse to the server, and select the above data source. Click "Test Connection" and all is well.
I then try to "Add Dataset". In the dialog, I select "Use a dataset embedded in my report", I select my data source added above, type in the SQL string and click OK. The "Enter Data Source Credentials" appears. No matter what permutation of valid domain (like the domain admin account and others) or SQL Server (like the 'sa' account) credentials plus checkboxes I use, I get an "Unable to connect to data source".
Security settings on the shared data source allow BUILTIN\administrators and domain\administrator all roles. The data source does work, as some legacy migrated reports run fine. Report Builder says the data source connects okay. But, I cannot create new reports, nor modify existing ones.
Any suggestions?