Error with Formatting Partition (Late 2012 Mac Mini)

Hello,

For some reason, i am getting an error when i have followed the 'Boot Camp Installation & Setup Guide' which i downloaded and printed, and its from Apple. The error is that when i get to the bit on the Windows 8 Pro installation, where you have to select the Partition called BOOTCAMP. I click the partition titled BOOTCAMP, and i click 'Drive options (Advanced)' and then i click 'Format' and then i click 'Ok'. After i did this, the Next button is still not allowing me to click it. The error is that 'The selected disk has an MBR partition table...' it still even says this even though i have tried like 5 times.

Please help me!

Kind Regards,

Alex