I remember applying for a job for which I was perfectly qualified and that I very much wanted. The interviews went extremely well, I had outstanding references, but I didn't get the job. I was very disappointed. Three months later I was offered a job totally out of the blue that absolutely changed my life and my career for the good. If I had gotten the first job that I thought I wanted, I probably would not have been available to receive the second offer and my life could have gone in a very different direction. The Dalai Lama once commented that it is important to "remember that sometimes not getting what you want is a wonderful stroke of luck".
Sometimes that "wonderful stroke of luck" is the opportunity to learn or experience something new. It might be about learning how to let go. Or perhaps the lesson is to hold out for what you want and not settle for less... to change your decision making process in order to get what you really want. One question to ask is what is standing in the way of the manifestation. Maybe one of your core beliefs simply does not support your stated goals. Or possibly what you want is not in your best interest in terms of the bigger picture. Or maybe you are being guided to meet someone or see something that you might have otherwise missed.
A friend told me that when she asked for something she would state exactly what she wanted and then add the line: "This or something better". If you don't seem to be getting what you want consider choosing to believe that the something better is in process, either in the form of an opportunity or a lesson, and become willing to receive it as a blessing.