At the $ prompt, type: sudo chflags nohidden /Volumes/Promise\ RAID/ and press Enter. (If you have renamed the Promise RAID drive icon, then please type its name, instead of Promise RAID, after Volumes/. Tab Completion is a powerful feature, just type Pro and hit the Tab key to have it fill in the rest.)
Enter your password at the password: prompt.
At the next $ prompt, type: sudo killall Finder and press Enter.
All your Finder windows will close and reopen, and the Promise RAID volume icon should be visible again.
