Excel Tab Names

[PCorbitt]

I have created a paginated report in Report Builder from an excel spreadsheet containing information on eight regions of our company. Try as I may, I can't seem to name the tabs using the Region field. If I leave the Tablix PageName empty, the tab names appear as Sheet 1, Sheet 2, etc. but if I add the expression as generated by the program (First(Fields!Region.Value, "Dataset2"), the last Region name is used and the names are US Tri-State 1, US Tri-State 2, etc. I get the same result even if I pare down the expression to just  Fields!Region.Value. What am I doing wrong? 

[aduguid]

Are you using the PageName on a row group for "Region"?

Also, I'd try the following:

=Fields!Region.Value