You also need to remember that these employers are getting hundreds, if not more, resumes for the positions they post. Just because you feel you are a close match to their requirements doesn't mean that you will automatically get a call from them. When I was job hunting I didn't get calls from every company to which I applied. It is just the nature of the job hunt.
Also, in some cases when I did get a call, it was weeks after I had applied (sometimes longer).