try changing your code as below
Try
rs = "INSERT INTO [Duty Slip] VALUES(@ID, @DDate, @VehicleType, @RegNo, @Vehiclebookedfor, @Vehiclebookedby, @VisitPlace, @JourneyDate, @JourneyTime, @StartingReadingKM, @ReturnDate, @ReturnTime, @EndingReadingKM, @ACORNON-AC, @TotalKM, @Useddays...