Disk Management won't extend volume size after adding to RAID 5 array

Hello, I'm using Intel Rapid Storage Technology to implement a RAID 5 array. I just added a 4 disk drive to the array. Everything wnet OK until the final step: Using Windows disk management to increased the volume size. I've posted a screen shot below. The volume is named 'Media". When I right click it, the extend volume item is grayed out. I've checked everthing I can think of, and can't...