If you want to cancel/book your PRS ticket of LKO mail (and some other trains) at the last time (after 8.00 pm) here is a tip for you.
Go to the Current Reservation counter which is situated at the main entry of LKO station and cancel/book your ticket. It opens till 11:00 pm.
Please give due credits to the concerned person. :P
Source: Self and "Not Rem" :P ....!!
Once i was struck in the condition when my LKO mail ticket was not confirmed and chart was prepared, i accidently saw the current counter and asked the clerk for cancellation and he did it :)
A useful tip, kindly give the location of the current reservation counter in the Above blog
it is located at Lucknow charbagh Main entry Gate, just behind the pf #1, Train Display board and infront of SBI atm.