Hi,

The cancellation rule of railways say
If the ticket is presented for cancellation within four hours before the scheduled departure of the train and up to -
(i) Three hours, when the ticket is for a destination station up to 200 KM.
(ii) Six hours, when the ticket is for a destination station of more than 200 KM but up to 500 KM., and
(iii) Twelve hours , when the ticket is for a destination station of more than 500 KM., after the actual departure of the train, cancellation charges shall be 50 % of the fare subject to the min. flat rate mentioned in clause (a). Provided that for night train leaving between 21:00 hours and 06:00 hours
(actual departures), refunds shall be admissible at the station within the time limit specified above or within two hours after the opening of reservation office, whichever is later.
Now, if you have cancelled you ticket (confirmed or not!) in this timespan, you will be entitled only for 50% advance. Ideally, you should have waited for the train to depart, and then got the tickets cancelled.
The rule is:
REFUND FOR UNUSED WAIT LISTED OR RAC TICKETS
(1A) Subject to provisions of subrule (2), no cancellation charges shall be payable if a wait-listed or RAC ticket is presented for cancellation up to -
(i) Three hours, when the ticket is for a destination station up to 200 KM.
(ii) Six hours, when the ticket is for a destination station of more than 200 KM but up to 500 KM., and
(iii) Twelve hours , when the ticket is for a destination station of more than 500 KM.,after the actual departure of the train except for a deduction of a clerkage charge of Rs. 10/- per passenger.
Provided that for night train leaving between 21:00 hours and 06:00 hours (actual departures), refunds shall be admissible at the station within the time limit specified above or within two hours after the opening of reservation office, whichever is later.