Why isn't this msg box code working when Target.Value >1 - excel

Question

By using Concatenate to combine 6 entries and then evaluate them, my worksheet changes the value of cell AA1 to be greater than 1 when a duplicate entry of any other row has been made. The Excel formula works well, but I need help on the VBA side: The code below is part of a Private Sub Worksheet_Change(ByVal Target As Range) with many operations that continue to work perfectly, while this does nothing at all. I already have Conditional Formatting highlighting the duplicate row entries, but I need a msg box to tell users what they have done wrong and how to fix it.
Dim fng As Range
Set fng = Range("$AA$1")
If Not Intersect(Target, fng) Is Nothing Then
If Target.Value > 1 Then
MsgBox "You already entered this barrel -- Enter another barrel over the duplicate. If no more barrels, change Grade to X, amounts to 0, and Producer to Z ZZ", vbOKOnly, "OOPS!"
End If
End If
In case it makes more sense to see the entire code, he it is:
Private Sub Worksheet_Change(ByVal Target As Range)
Target.Worksheet.Unprotect Password:="Cami8"
Dim rng As Range
Set rng = Range("F3:F10001")
If Not Intersect(Target, rng) Is Nothing Then
Target.Offset(0, 4) = Now
ActiveWorkbook.Save
End If
Application.EnableEvents = True
Dim ung As Range
Set ung = Range("J3:J10005")
If Not Intersect(Target, ung) Is Nothing Then
Target.Offset(-1, -3).Locked = True
End If
Application.EnableEvents = True
Dim wng As Range
Set wng = Range("J3:J10005")
If Not Intersect(Target, wng) Is Nothing Then
Target.Offset(-1, -4).Locked = True
End If
Application.EnableEvents = True
Dim xng As Range
Set xng = Range("J3:J10005")
If Not Intersect(Target, xng) Is Nothing Then
Target.Offset(-1, -5).Locked = True
End If
Application.EnableEvents = True
Dim kng As Range
Set kng = Range("J3:J10005")
If Not Intersect(Target, kng) Is Nothing Then
Target.Offset(-1, -6).Locked = True
End If
Application.EnableEvents = True
Dim qng As Range
Set qng = Range("J3:J10005")
If Not Intersect(Target, qng) Is Nothing Then
Target.Offset(-1, -7).Locked = True
End If
Application.EnableEvents = True
Dim cng As Range
Set cng = Range("C3:E10001")
If Not Intersect(Target, cng) Is Nothing Then
Application.EnableEvents = False
Target.Value = UCase(Target.Value)
Target.NumberFormat = "General"
Application.EnableEvents = True
End If
Dim sng As Range
Set sng = Range("E3:E10002")
If Not Intersect(Target, sng) Is Nothing Then
If Len(Target) > 1 Then
MsgBox "You entered GRADE with a letter and a space -- Click on the cell and enter only a letter", vbOKOnly, "OOPS!"
End If
End If
Dim fng As Range
Set fng = Range("$AA$1")
If Not Intersect(Target, fng) Is Nothing Then
If Target.Value > 1 Then
MsgBox "You already entered this barrel -- Enter another barrel over the duplicate. If no more barrels, change Grade to X, amounts to 0, and Producer to Z ZZ", vbOKOnly, "OOPS!"
End If
End If
Target.Worksheet.Protect Password:="Cami8"
End Sub

Answer 1

Thanks for the great tip about Worksheet_Calculate, since that did the trick! I just removed the code I had in Worksheet_Change and input this:
Private Sub Worksheet_Calculate()
Const lVal As Long = 2
Dim rCell As Range
Set rCell = Range("AA1")
If rCell.Value = lVal Then
MsgBox "You already entered this barrel -- Enter another barrel over the duplicate. If no more barrels, change Grade to X, amounts to 0, and Producer to Z ZZ", vbOKOnly, "OOPS!"
End If
End Sub