mandatory cells

Thanks bakerman2 but the message must be referred to the cell to be inserted

Hi harrisonland your modified:

Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

Dim cella As Range
Application.EnableEvents = False

'Set cella = Range("A3") '<<< cella singola
'Set cella = Cells(Target.Row, Target.Column) '<<< colonna

Set cella = Cells(Target.Row, 1) '<<< cella singola

With cella
If .Value = "" Then

'MsgBox "Devi inserire una data nella cella  A" & Target.Row & " ", vbCritical, "Errore!"
MsgBox "You must enter a date in cell A" & Target.Row & " ", vbCritical, "Errore!"
cella.Select
Application.EnableEvents = True
Exit Sub
End If

End With


Set cella = Cells(Target.Row, 2) '<<< cella singola

With cella
If .Value = "" Then

MsgBox "Devi inserire il reparto nella cella  B" & Target.Row & " ", vbCritical, "Errore!"
cella.Select
Application.EnableEvents = True
Exit Sub
End If

End With



Set cella = Cells(Target.Row, 3) '<<< cella singola

With cella
If .Value = "" Then

MsgBox "Devi inserire l'operatore nella cella  C" & Target.Row & " ", vbCritical, "Errore!"
cella.Select
Application.EnableEvents = True
Exit Sub
End If

End With



Set cella = Cells(Target.Row, 4) '<<< cella singola

With cella
If .Value = "" Then

MsgBox "Devi inserire il tempo nella cella  D" & Target.Row & " ", vbCritical, "Errore!"
cella.Select
Application.EnableEvents = True
Exit Sub
End If

End With



Application.EnableEvents = True
End Sub

work well.
Thans you
xam