Dear Ashok,
Greetings!
RKE_SELECT_FACTDAYS_FOR_PERIOD is giving correct output for me. Please select proper I_FACTID value based on your requirement.
If you still have any problem, please post the error (if any) or the input that you gave and the output you got in detail, so that we can also check and let you know.
Number of working days between two dates | SCN
Regards,
Shankar.