You should always contact the Admissions Director and ask how you can strengthen your app. Many of the comments made thus far are spot on - you need to be a good fit for the professors, you need to have a different perspective on an area of research, and funding controls everything - not who you know. Our ad com folks work hard and are thorough; they would admit more applicants if they could, believe me. No one is happy about declining so many excellent students and everyone is interested in securing the future of their programs by admitting as many strong applicants as possible. This process is not fun for anyone - you or us.