Consider the following scenario:
You create a report in a Microsoft SQL Server 2012 Reporting Services (SSRS 2012) project, and the report uses SQL Server as the data source.
You make sure that the dataset retrieves a SQL Server stored procedure with required parameters.
You click the Refresh Fields button.
In this scenario, the stored procedure returns NULL values, and you are not prompted to enter any parameter values.
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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.