Getting confirmed tatkal ticket from IRCTC site is like winning a gold medal. I have tried to get tatkal ticket hundreds of times but most of the time I was unable to get the tatkal ticket. And yes, I was always unfortunate at times when it was real emergency.
Daily thousands of needy people use IRCTC in the morning to get a tatkal ticket but a large percentage of them never got the success. The main reason of the failure of getting the tatkal ticket is either you were just 1-2 minutes late or the window says “session expired”.