Can't create new RAID1 volume in Intel Rapid Storage

I have a Gigabyte GA-P55A-UD4 motherboard and I am attempting to create a new RAID1 volume, but the option for creating new volume is not available in the status screen. Windows 7 64-bit Ultimate, 12.5.0.1066 drivers. The system has one existing RAID1-volume, two new 3TB drivers that I am attempting to use in the new RAID1 volume, one additional hard drive and a DVD-drive (ie. all six ports in use).