Some time ago I contacted a professor at another university and, after some discussions, he agreed to supervise me and told me to make a formal application to the department. Unfortunately, the admission committee rejected my application. I asked that professor why, and he said he had no idea and I don't know if he tried to follow my application.
I am sure I meet the program's minimum requirements, submitted all necessary documents and even indicated that professor as a supervisor in a dedicated field. I would like to ask if I can do something, like making an appeal (although the department has no such thing), or keeping on sending email to the professor? Is this situation common?