There's a new type of Cryptowall come out in October (Cryptowall 2) ... http://www.bleepingcomputer.com/virus-removal/cryptowall-ransomware-information#cryptowall2 ... which we believe might have been the version you had, and as far as I'm aware CryptoPrevent has not yet been updated to be effective against it.
Obviously they're working on an update to block the new version, but quite when that will be ready we can't say at this point.
Obviously they're working on an update to block the new version, but quite when that will be ready we can't say at this point.