It is unfortunate that Harold Camping, for all his claims to teaching the Bible, never grasped what Jesus made clear in Mark 13 as evidenced by this excellent word from James R. Edwards:
Most importantly, Mark 13 admonishes readers against attempts at constructing timetables and deciphering signs of the Parousia. Disciples are admonished to be alert and watchful (vv. 5, 9, 23, 33, 35, 37), reminded that they do not know the time of the end (vv. 33, 35), and warned not to be led astray by even the most obvious signs (vv. 5, 6, 21, 22), for the end is not yet (vv. 7, 13). No one is either encouraged or commended for attempting to be an eschatological code-cracker. That is folly, for even the Son of Man is ignorant of the End (v. 32). The premium of discipleship is placed not on predicting the future but on faithfulness in the present, especially in trials, adversity, and suffering.
(James R. Edwards, The Gospel According to Mark, The Pillar New Testament commentary [Grand Rapids: Eerdmans, 2002], p. 386.)