IB is doing there best on the base of the samples they received from the site of bomb blast....It is very hard to find this kind of informaton before it happens...Believe me 4 out of 10 times the do crack the information and avoid bombing.....but it is not possible everytime..... If somebody wants to do sucide with bomb how can you prevent it...he will just blow him self, there is no way to find out who is going to do what at what time.
