Facebook Friend Requests can't go through; what can I do? am I doing something wrong?

[jirmantogo]

On Facebook, I click the "Add Friend" Button the person's page, but it gives me the following error message: "Friend Request Can't Be Sent. Do you know this user personally? To prevent misuse of Facebook, this request can't be sent. To learn more, please visit the Help Center. If you believe you're seeing this message in error, you can report the problem." I get this error message for each person I try to add as a friend on Facebook. Did I do something wrong? Can I not add friends again on FB? I have not done anything abusive on here. Now here is the thing, there are kids who I know and we know each other well, I send them a friend request in the past, but they never accept the friend request. Could I be getting the message because the request has gone unanswered?" What can I do here? Any advice from you guys?
Thanks