Yes, the Jchen's answer is accurate, look, let me telling you what you need to do for approval a request of anyone, firstly when a person add you in his friend list, the website sends you a message saying you, what a person has added you in his friend list, later, when you sign on again on the website, immediately appear a dialog box with the legend that you need enter to your need go to your profile and later in the section where say Control Panel, later you need find the other section named NETWORKING in this part you need give a click in the section CONTACTS & FRIENDS, there in that part you will see all your friends the website from, in that same section you will can add or remove friends, well, I hope my help to be of useful for you.
well try again....go to Notifications, Incoming Friends Resquests, then go to the bottom and check the small box and press save changes. did you do that? if you did and it still didn't work, you will have to tell Mr. T ( David, or Tomisimo)