Technically speaking, surveillance is a manual work carried out by a human being. It is like a hunting game. There is no 100% success rate with one chance. But usually, our success rate is around 96% at the first attempt. At least, we would be successful eventually in the long run if we are allowed to try the second attempt or more.Some of the elements that are likely to cause the interruption of surveillance are as follows;– The subject hails a taxi suddenly in the middle of a street.– Someone pick up the subject at a station right after he/she reaches the station.– The subject entered a big convert stadium where there are more than 5 exits.– The subject is too vigilant to follow.