Link PivotTable Page Fields

I have a workbook with three sheets. The first is a list of employees with their managers. The second is the data about those employees (who they sold product to, and how much, on what date). The third is the PivotTable with the employees' sales. I have the Customer name in the Row field, and the amount in the Data field. I have two page fields - the Manager's name and the Employee's name. The example that I'm using so as not to violate my NDA is a Northwind knockoff. That's why the names probably sound familiar.

What I want to do is have the second pivottable page field (Employee) change, so that when I choose a manager's name, only the employees who report to that manager show up in that page field. I have a named range called "allEmp" (all employees), one called "buchanan" (all the employees who report to Steven Buchanan), one called "fuller" (all the employees who report to Andrew Fuller). (File attached, btw).

Private Sub Worksheet_Calculate()
Dim mgrRange As Range
mgrRange = Range("allEmp")
Range("$b$1").Select
Select Case ActiveCell.Value
Case "Andrew Fuller"
ActiveWorkbook.PivotTable("EmpSales").PivotFields("Employee").CurrentPage = Range("fuller")
Case "Steven Buchanan"
ActiveWorkbook.PivotTable("EmpSales").PivotFields("Employee").CurrentPage = Range("buchanan")
Case "Susan Erickson"................