Not getting selected does not mean incapability
There is stiff competition nowadays in every competition as the positions are limited but there is a big rush of qualified candidates who try their best to compete and get through. In such a situation there are a large number of candidates who do not get success but they are very near in merit to those who got selected.So the gap between those who are selected and some of those who are not selected is very narrow. Such students who are near the cut-off limit should not get disheartened and demotivated because it is due to the huge crowd of candidates that such things happen. So they should not undermine their capabilities and try for other exams and other opportunities.
I strongly feel that one should not be discouraged by such setbacks in life.