There is nothing wrong in your being unhappy because you are not happy. Let your search for happiness go on. One should, however, realise that one can't be happy all the time because of various factors, internal as well as external. Therefore, one has to understand why one is unhappy.
If you know the cause and you can redress it or can ignore it, then happiness is yours. That is for sure.
Prafulla Raval and Vasant Raval address this oft-discussed issue in their book, Finding Soul in Work and Life. We live most often unexamined and disconnected lives, thereby denying ourselves the realisation what is there behind our problem. And that most of the things we think about in daily life are not absolute but relative.
If you are happy today, it is because something good has come about. But that state of mind can't be permanent. You are bound to lose interest and happiness in repeated experiences of the same kind. If you have read 1,000 Places to See Before You Die by Patricia Schultz, you will recall it reminds you the more you become greedy and expand your worldly desire, the more you are caught in the state of unhappiness.
One must understand that being unhappy is not a bad thing but quite a normal one. You can become happy only if you are unhappy. All of us, or most of us, get disappointed at one time or the other.
But you have to realise that you have to be within the normal limit of unhappiness and that such a state of mind should not drive you to frustration and madness. A normal state of being unhappy is a positive sign of an aspiring and progressive mind.
A purpose-driven life has to have a different direction - one of complete self-control of mind to take the desired course with an action plan. As James Trustlow Adams said, "Man can alter his life simply by altering his attitude of mind."
And, remember, only a moron can be happy all the time.