I just wanted to pipe in that I was having difficulty with this issue on Windows 7 and the problem was having a partition on the SSD as ajb suggested. Afterward, the accelerate partition isn't visible in "Disk Management" so my guess is it's a Linux ext partition managed by the chipset.
The missing steps as I've seen them are:
1. Both disks need to be in RAID mode (although not configured) if your Windows is installed on a disk in AHCI or IDE mode you will need to follow the steps in this post to switch to RAID mode [How to: Change SATA Modes After Windows Installation]
2. The SSD you intend to have as your cache needs to have unpartitioned space (up to 64GB)
3. Accelerate will use up to 64GB (on the H87) of space on the SSD and you can now go into "Disk Management" and partition the rest of the space for whatever you want.