Splitting Workbook into separate workbooks including all tabs - vba

Question

I looked at Bhaskar's code on the post located here (VBA code to split an excel file into multiple workbooks based on the contents of a column?)
and have modified it to the point where it recognizes the field I need the workbooks split on but I am getting a variable not defined error at the following section
For Each rw In UsedRange.Rows
I appreciate any help you could provide
I have included the code.
Option Explicit
Dim personRows As Range 'Stores all of the rows found
'Split data into separate columns baed on the names defined in
'a RepList on the 'Names' sheet.
Sub SplitSalesData()
Dim wb As Workbook
Dim p As Range
Dim counter2 As Integer
Dim i As Integer
counter2 = 0
i = 0
Application.ScreenUpdating = False
' in my case i am generating new excel based on every 8 reacords from begining. You can simplyfy this logic based on your need.
For Each p In Sheets("Source").Range("AM1") ' Give the name of your input sheet and column
If i = 0 Then ' We are starting, so generate new excel in memeory.
Workbooks.Add
Set wb = ActiveWorkbook
ThisWorkbook.Activate
End If
WritePersonToWorkbook wb, p.Value
i = i + 1 ' Increment the counter reach time
If i = 8 Then ' As my need is after processing every 8 uniqe record just save the excel sheet and reset the processing
counter2 = counter2 + 1
wb.SaveAs ThisWorkbook.Path & "\salesdata_" & CStr(counter2) ' save the data at current directory location.
wb.Close
Set personRows = Nothing ' Once the process has completed for curent excelsheet, set the personRows as NULL
i = 0
End If
Next p
Application.ScreenUpdating = True
Set wb = Nothing
End Sub
'Writes all the data rows belonging to a RepList
Sub WritePersonToWorkbook(ByVal SalesWB As Workbook, _
ByVal Person As String)
Dim rw As Range
Dim firstRW As Range
For Each rw In UsedRange.Rows - ***ERROR IS HERE***
If Not Not firstRW Is Nothing And Not IsNull(rw) Then
Set firstRW = rw ' WE want to add first row in each excel sheet.
End If
If Person = rw.Cells(1, 5) Then ' My filter is working based on "FeederID"
If personRows Is Nothing Then
Set personRows = firstRW
Set personRows = Union(personRows, rw)
Else
Set personRows = Union(personRows, rw)
End If
End If
Next rw
personRows.Copy SalesWB.Sheets(1).Cells(1, 1) ' Adding data in Excel sheet.
End Sub