DE1 Clock divide by 2

Hi, I am trying use an MIF file's Data (1s and 0s) and feeding it into the WM8731 on DE1 Starter Kit Board I am trying to use the on-board clock of 24MHz and halving it by writing to the "Sampling Control" register but it seems to be not working for me. I am wondering that is there something else needs to be done before I can half the employed clock frequency?

Please Help,

Regards.