Automatic mail on due date (30 days or closer)

I am trying to do a vba script so that i run excel using microsoft scheduler and if it finds something which is due in 30 days it will auto0matically send a mail. now for the first column its working fine but for the second it stops. can anyone help me please

Sub Workbook_Open()
 
Dim lngLast As Long
Dim lngCounter As Long

Application.ScreenUpdating = False
lngLast = Cells(Rows.Count, "AB").End(xlUp).Row
For lngCounter = 2 To lngLast
  With Cells(lngCounter, "AB")
 If DateDiff("d", Date, .Value) <= 30 Then
        *** = "A" & .Row
      ass2 = "B" & .Row
      ass3 = "AB" & .Row
    firstdate = Range(ass3).Value
msg = DateDiff("d", Date, firstdate)
 Set objEmail = CreateObject("CDO.Message")
        
        With objEmail
            With .Configuration.Fields
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") _
                    = "smtp.go.net.mt"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") _
                    = "30"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendusing") _
                    = "2"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") _
                    = "25"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendemailaddress") _
                    = "instrumentation@aurobindomalta.com"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") _
                    = "0"
                .Update
            End With
            .To = "medio@onvol.net"
            .From = "instrumentation@aurobindomalta.com"
            .Subject = "Calibration due for" & Space(2) & Range(***).Value
            .TextBody = Range(ass2).Value & "(" & Range(***).Value & ")" & Space(2) & "has its calibration  due in" & Space(2) & msg & Space(2) & "days. Kindly contact personell in charge."
          
            .send
        End With
        Set objEmail = Nothing
End If
End With
Next lngCounter
Application.ScreenUpdating = True
cal
End Sub

Sub cal()


Dim lngLast As Long
Dim lngCounter As Long

Application.ScreenUpdating = False
lngLast = Cells(Rows.Count, "AC").End(xlUp).Row
For lngCounter = 2 To lngLast
  With Cells(lngCounter, "AC")
 If DateDiff("d", Date, .Value) <= 30 Then
      *** = "A" & .Row
      ass2 = "B" & .Row
      ass3 = "AC" & .Row
    firstdate = Range(ass3).Value
msg = DateDiff("d", Date, firstdate)
       Set objEmail = CreateObject("CDO.Message")
        
        With objEmail
            With .Configuration.Fields
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") _
                    = "smtp.go.net.mt"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") _
                    = "30"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendusing") _
                    = "2"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") _
                    = "25"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendemailaddress") _
                    = "instrumentation@aurobindomalta.com"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") _
                    = "0"
                .Update
            End With
          
            .To = "medio@onvol.net"
            .From = "instrumentation@aurobindomalta.com"
            .Subject = "Calibration due for" & Space(2) & Range(***).Value
            .TextBody = Range(ass2).Value & "(" & Range(***).Value & ")" & Space(2) & "has its calibration due in" & Space(2) & msg & Space(2) & "days. Kindly contact personell in charge."
          
            .send
        End With
        Set objEmail = Nothing
    End If
  End With
Next lngCounter
Application.ScreenUpdating = True

pm

End Sub

Sub pm()


Dim lngLast As Long
Dim lngCounter As Long

Application.ScreenUpdating = False
lngLast = Cells(Rows.Count, "AD").End(xlUp).Row
For lngCounter = 2 To lngLast
  With Cells(lngCounter, "AD")
If DateDiff("d", Date, .Value) <= 30 Then
      *** = "A" & .Row
      ass2 = "B" & .Row
      ass3 = "AD" & .Row
    firstdate = Range(ass3).Value
msg = DateDiff("d", Date, firstdate)
       Set objEmail = CreateObject("CDO.Message")
        
        With objEmail
            With .Configuration.Fields
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") _
                    = "smtp.go.net.mt"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout") _
                    = "30"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendusing") _
                    = "2"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") _
                    = "25"
                .Item("http://schemas.microsoft.com/cdo/configuration/sendemailaddress") _
                    = "instrumentation@aurobindomalta.com"
                .Item("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate") _
                    = "0"
                .Update
            End With
            .To = "medio@onvol.net"
            .From = "instrumentation@aurobindomalta.com"
            .Subject = "Performance monitoring due for" & Space(2) & Range(***).Value
            .TextBody = Range(ass2).Value & "(" & Range(***).Value & ")" & Space(2) & "has its performance monitoring  due in" & Space(2) & msg & Space(2) & "days. Kindly contact personell in charge."
          
            .send
        End With
        Set objEmail = Nothing
    End If
  End With
Next lngCounter
Application.ScreenUpdating = True

End Sub

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