Darryl Harper hasn't had his carrots

Dump this man from the umpire's panel. Now, he's given Brendan Nash out after Aleem Dar rightly turned down an LBW appeal for a ball that struck him above the knee-roll, and then appeared on the replay to be going over the stumps. As Michael Holding pointed out on air, if the third umpire is in so much doubt about whats going on, why is he willing to over-turn an on-field decision? Does Harper not understand the rules?