I used ReportItems."FieldName".Value to get the value to show in the header.
When grouping by that FieldName Value, the value changes on every page break on the ReportViewer.
The problem is that when I export the Excel spreadsheet, the FieldName Value shown on the spreadsheet is the first FieldName Value and that same value is shown on every worksheet. Each worksheet tab pagename has the correct FieldName Value, it's just the value on the header repeats the first occurance of the FieldName Value.
