There are several reasons I see on why people remain unemployed. First of which is the most difficult truth - there is no job matching one's qualifications. There are a lot of companies hiring for several different positions but it does not mean they would hire you. First they would take a look if you are a fit to that position. Considerations are field of specialization, degree in college, length of experience and a whole bunch of items.
Yes, you fit the qualifications for the job for a single company, but why do you still have no job? This would point you to the next issue. Attitude. They would invite you for exams and you would pass them with flying colors so you're bound for the interview. But come interview time, they don't like what they see (not the physical aspect - unless you're applying to be a model or a showbiz figure). Manners, etiquette and personal well-being are of course being considered. You may be the brightest from all the other aspirants but if they see you're a bad-ass individual who just thinks about himself, then say bye-bye to your application. If they see you have the traits that would fit you to work within their organization, then you're up to the next level.
Okay, so you're done with the 2nd barrier but why still unemployed? You would now look into the compensation package (although I know a lot look at this at the first point). You tend to ask for more. In today's financial crisis, taking something relatively lower in value would be better than having no job at all. Having a scrape of about 10% of your asking salary might be able to seal the deal in your job hunting. Fine, you saw that the gross pay is good, but what about the other benefits? Make sure if you accept a job, you're looking for the further time ahead.
Those are the 3 big issues I am seeing on why you remain unemployed. 1. Job Fit; 2. Attitude; 3. Salary. What you have to do is to check a balance of the three. You might not get all the ideals on the 3 aspects but make sure you know how to play the game. Leverage your strengths. Don't be afraid to admit weaknesses but make sure you assure them that there are other things in you that could easily overshadow those flaws.
Happy Job Hunting!!!