Why won't facebook let me add ONE person?

I am trying to send a friend request to an old high school friend, but an annoying message keeps popping up that says, "Do you know this user personally? To prevent the misuse of facebook, this request can't be sent, visit the help center for more information." It is so annoying and it's pissing me off. Maybe over the past week I have sent to many friend requests to people, so that is why this is happening. Is there any way to fix it?