Check File Path Of Before Running Macro

I have a spreadsheet with a macro that saves a backup s/s to a particular folder, but the problem I have need the macro to check the filepath is that of the original s/s before running.

Its so that when people take copies of the main s/s and save them to their desktop I dont want the copies being saved in the backup folder

macro is below

Private Sub Workbook_BeforeClose(Cancel As Boolean)

If ActiveWorkbook.ReadOnly Then Exit Sub

If MsgBox("Do You Want To Save A Backup?", vbYesNo) = vbNo Then Exit Sub

Dim fso As Object
Dim objFiles As Object
Dim myWkBk As String
Dim myFName As String
Dim BkUpDir As String
Dim CountFiles As Integer
Dim mydate As Double

BkUpDir = "k:singstatappealsappeals trackerBackups"

Set fso = CreateObject("Scripting.FileSystemObject")
Set objFiles = fso.GetFolder(BkUpDir).Files

On Error Resume Next
'the actual counting of files takes place here.
If Err.Number 0 Then
CountFiles = 0
Else
CountFiles = objFiles.Count
End If


If CountFiles > 4 Then
MsgBox "You have " & CountFiles & " saved workbooks. Perhaps you should delete some?"
End If

mydate = Format(Now(), "ddmmyy")
myWkBk = ActiveWorkbook.Name
myFName = ActiveWorkbook.FullName

fso.CopyFile myFName, BkUpDir & mydate & myWkBk

End Sub