RST "unknown error" while enabling acceleration

My setup:

intel DZ68C motherboard with i7-2700k CPU

Samsung 850 PRO 256GB SSD boot

Western Digital Black 2TB HDD files

Intel X25-M G2 80GB SSD cache drive

Win 7 Ultimate 64bit

RST 11.7.0.1013

SATA is set to RAID, all drives seem to show as expected:

I head to the "Accelerate" tab and select to accelerate the HDD:

I get about a minute of the spinning hourglass, and this error:

So far, I've uninstalled/re-installed RST 11.7.0.1013, "Reset to available" the cache drive, reboot, try again, I get same result.

Found a post advising to shrink the volume to be accelerated, leaving ~100MB unallocated, which I did, but still same result.  Here's the disk manager view of my drives: