Private Sub Form_Open(Cancel As Integer)
  
strDate = InputBox("Lutfen Puantaj Giris Tarihini Giriniz!!!", "Main Database") ',Format(Now() - 1, "dd/mm/yy"))
    
If strDate = "" Then Cancel = True: Exit Sub
If CDate(strDate) < Now() - 7 Or CDate(strDate) > Now() Then MsgBox strDate & " is wrong date.You can't enter this date", vbCritical: Cancel = True: Exit Sub
              
    strDate = Format(strDate, "MM/dd/yyyy")

    Me![Tarih].DefaultValue = "#" & strDate & "#"
    
        TimerStartTime = Now()
           
    End Sub

Private Sub Form_Open(Cancel As Integer) 'bu satırın altına aşağıdaki satırı ekleyin
On Error GoTo hata

hata:
Exit Sub
End Sub

If IsDate(strdate) = False Then
MsgBox ("Geçersiz tarih")
Exit Sub
End If