VBA code doesn't run when cell is changed by a formula

Question

Worksheet A has ranges of data that are collected from Worksheet B. Worksheet A has a macro that calculates if the data is above a value then calls an email module to email selected users.

When the data is manually input on Worksheet A the Macro works, however when data is pulled from Worksheet B it doesn't fire.

I'm not sure what I need to change in my VBA code.

Private Sub Worksheet_Change(ByVal Target As Range)
    Call MailAlert(Target, "B5:M5", 4) 
    Call MailAlert(Target, "B8:M8", 7) 
    Call MailAlert(Target, "B11:M11", 6)
    Call MailAlert(Target, "B14:M14", 2) 
    Call MailAlert(Target, "B17:M17", 4) 
    Call MailAlert(Target, "B20:M20", 1) 
    Call MailAlert(Target, "B23:M23", 3) 
    Call MailAlert(Target, "B26:M26", 1) 
    Call MailAlert(Target, "B29:M29", 5) 
    Call MailAlert(Target, "B32:M32", 1) 
    Call MailAlert(Target, "B35:M35", 7) 
    Call MailAlert(Target, "B38:M38", 20) 
    Call MailAlert(Target, "B41:M41", 0) 
End Sub

Private Sub MailAlert(ByVal Target As Range, ByVal Address As String, ByVal Value As Integer)
    If Target.Cells.Count > 1 Then Exit Sub
    If Not Application.Intersect(Range(Address), Target) Is Nothing Then
        If IsNumeric(Target.Value) And Target.Value > Value Then
        Call Mail_small_Text_Outlook
        End If
        Application.EnableEvents = True
    End If
End Sub

Answer 1

To capture the changes by a formula you have to use the Worksheet_Calculate() event. To understand how it works, let's take an example.

1. Create a New Workbook.
2. In Sheet1 Cell A1, put this formula =Sheet2!A1+1

Now In a module paste this code

Public PrevVal As Variant

Paste this in the Sheet Code area

Private Sub Worksheet_Calculate()
    If Range("A1").Value <> PrevVal Then
        MsgBox "Value Changed"
        PrevVal = Range("A1").Value
    End If
End Sub

And lastly in the ThisWorkbook Code area paste this code

Private Sub Workbook_Open()
    PrevVal = Sheet1.Range("A1").Value
End Sub

Close and Save the workbook and reopen it. Now Make any change to the cell A1 of Sheet2. You will notice that you will get the message box MsgBox "Value Changed"

SNAPSHOTS

Answer 2

The worksheet_change event will only fire on manual user changes. I think your best bet would be to implement this as a worksheet change event on your Worksheet B, where I presume the user input changes are taking place.

There are some alternatives which I'll suggest if this really doesn't suit you, but I think this is probably by far the best option.

Edit: Another suggestion per following comments

The ThisWorkbook object has an event SheetChange, which will be fired any time any sheets in the workbook are changed. If you can identify the ranges where data will be entered on each of the B sheets you can then use these ranges as in your original code.

Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
    If Not Sh Is Sheets("Worksheet A") Then
        If Intersect(Sh.Range("B1:B5"), Target) Then
            'Call MailAlert as required here
        ElseIf Intersect(Sh.Range("B10:B20"), Target) Then
            'Call MailAlert as required here
        Else ' Etc...
            'Call MailAlert as required here
        End If
    End If
End Sub

Let me know how that goes.