Kalka Mail not getting LHB due to 2 Reasons.
1. Train Shunting Procedure at Chandigarh. (Only half coaches go to Kalka), LHB Trains can't have Slip Cowches because detaching, attaching requires Couplings to open which is hard procedure.
2. Short PF length at Kalka.
Here, 1st reason is more important than 2nd