Date and Dateserial functions in Crystal Reports

I found a solution for my date problem in Crystal reports after 15 days of investigating.

The Date function of Crystal Reports requires arguments of year, month and day in that order as Date(y,m,d). But the Date function fails if there are special cases.

The dateserial function behaves in a similar way to Date function but is more tolerant

For example a value larger than 12 or less than one will still calculate a valid month, and will adjust the year correctly if DateSerial(y,m,d) is used.
Days work in a slightly different way. A value of 0 gets the last day of the previous month. This makes sense if you think that 1 gives you the first of the month, so 0 must get the day before.

For more information on functions in Crystal REports you can visit here