MS Excel - How to Vlookup an Autofilter criteria result

In the attached file, there is a function which returns the result of an Autofiltered column.  I am now using that to reference the value and then use a VLookup to find data.  I'm getting #N/A results.
... last minute insight.  Is the problem because the code is returning a string and I'm looking for a number to match in the VLOOKUP?  If so, is there a way to change this in the VLookup?  If not, can you help with a solution?
Many thanks.

Function AutoFilter_Criteria(Header As Range) As String
    Dim strCri1 As String, strCri2 As String
    Application.Volatile
    With Header.Parent.AutoFilter
        With .Filters(Header.Column - .Range.Column + 1)
            If Not .On Then Exit Function
                strCri1 = .Criteria1
            If .Operator = xlAnd Then
                strCri2 = " AND " & .Criteria2
            ElseIf .Operator = xlOr Then
                strCri2 = " OR " & .Criteria2
            End If
        End With
    End With
    AutoFilter_Criteria = Right(strCri1, Len(strCri1) - 1)

End Function

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drillDown.xls