How to: Refresh Fields in the Datasets Window (Report Designer)
When designing a query in Report Designer, use the Datasets window to check that your query defines the expected set of fields for a dataset. To refresh the contents of the Datasets window, you must save the changes to the report definition file.
When designing a report layout, use the Datasets window to see which fields are available for use in your report. Only data represented by fields in a dataset can be included in your report.
There are several ways you can refresh the fields in the Datasets window to reflect the current contents of the report definition.