a1 and a2 ram slots not working

Hi, I have bought Asrock Xtreme 11 motherboard with 'Gskill Trident X F3-2400C10Q-32GTX RAM'. mobo has 8 dimm slots namely a1,a2,b1,b2,c1,c2,d1,d2. The problem is c1 is not working. I checked individual ram sticks and they are working perfectly. But whenever i insert any stick into c1, it is...

16 GB DIMMs must be installed in slots numbered A1, A2, A3, A4, B1, B2, B3, and B4 and 8 GB DIMMs must be installed in slots A5, A6, B5, and B6.

Why is my RAM slot not working? Your RAM slot may not be working because of an incompatible RAM, a broken slot, bent pins in….