If you are interviewing with the start-up founders, the #1 reason you are not hired is the salary you request. If you are interviewing with the lead developers, #1 reason you are not hired is that they felt you are better than themselves and you could replace them so don't make them feel that any way.
Do not put hope in any of the interviews. If you are told that they will get back to you, expect nothing and if you are told that they will get back to you, for say, in 2 weeks, either negative or positive, again, expect nothing. Just apply as many jobs you can and go to interviews if you are called and then wait. Eventually, if you are a good developer, you will get a job.
Another thing is experience. If you don't have any working experience, be patient for a little while and work less than a salary you'd request normally and after a long time such as a year passes, start looking for a new job when you are still working. Then you'll get a better job.
