[cobbler] gpt partition

Dear all, I have to use the GPT partition because my disk array is bigger than 2TB. I am using CentOS 6.5 and cobbler 2.6.3. I added the pre section in my kickstart to create a partiotion with parted command, but it didn't work. I looked for on Internet but I can't find the error. Part of my kickstart is below. What do I do wrong? ... # Disk clearpart --none part /boot --fstype="ext4" --onpart=sda1 part swap --onpart=sda2 part / --fstype="ext4" --onpart=sda3 %packages ... %end %pre parted -s /dev/sda mklabel gpt parted -s /dev/sda unit MB mkpart primary 1 300 parted -s /dev/sda unit MB mkpart primary 300 1024 parted -s /dev/sda unit MB mkpart primary 1024 -1 parted -s /dev/sda set 1 boot on parted -s /dev/sda set 2 swap on %end Best regards, Bino