Same issue here, but with RockedRaid 622 on Mac Pro (early 2009 model)
I'd used the Yosemite Developer builds, and the earlier builds did work up until a new version of the /Library/Extensions/HighPointRR.kext was included.
The version that worked was 4.0.0, dated 8/7/2013. The new version that seems to have broken things is version 4.3.3, dated 8/14/2014.
You can check to see if the driver is actually loading by starting up the 'System Information' app, and looking for Extension 'HighPointRR', under 'Software / Extensions'. It will tell you if it's actually loaded or not. (Also, you can look for the card itself in 'Hardware / PCI'... This will tell you if the driver is loaded or not.)
I filed a bug (18660476), but its marked as 'Duplicate of 18352315 (Closed)'... If I try to search for 18252315, I don't get any results, so I can't see what they're referencing. (Maybe it's an internal bug report?)
As a workaround, I was able to copy the older (version 4.0.0, from 8/7/2013) 'HighPointRR.kext' over the new one in '/Library/Extensions'. That seems to work okay, but every time OS X updates it overwrites the older kext with the newer version...