I've found the problem... from the Audacity website:
On 64-bit versions of Windows, sound device drivers specific to the 64-bit operating system are essential. If upgrading from a 32-bit to 64-bit operating system, a 64-bit capable computer is required, and the sound device drivers must also be updated to a 64-bit version.
So while the Audacity program itself is 32bit, because it's running on a 64bit operating system, it requires 64bit drivers for the DJM, which aren't available at this time.
Your only option would be to use another software to record until Pioneer releases 64bit drivers.