Hi, I am trying to make a field in a sheet mandatory so that when the user clicks a button I have added to take them to another sheet they are prompted that they must fill in a particular cell.

I have used the following code before to make a field compulsary before the user closes the whole file but I don't know how to adapt it to work when they leave the sheet:

Private Sub Workbook_BeforeClose(Cancel As Boolean)
Dim checkRng As Range
Set checkRng = Sheets("Sheet1").Range("A1")
If checkRng.Value = "" Then
Cancel = True
MsgBox "Please fill in " & _
checkRng.Address(False, False) & "."
End If
End Sub


Any help would be very much appreciated, thanks