There may be various reasons behind this. The management may decide not to fill up the vacancy at present. This happens when the company undertakes cost-cutting measures and doesn't fill up the vacancies. On the other hand, if the company decides to interview some more candidates for that particular position, they may put on hold the announcement of result (i.e., declaring the name of successful candidate) for the time being.
Best of luck to you! However, I would advise you not to wait for this particular position and try your luck in other similar organisations.