Can't get the remote audio recording device

Hi,

Setup:

1. VMware ESXi set up to look like Windows 7 Enterprise (my terminology is all wrong, I know. I hope I am making sense).
2. An external Windows 7 Enterprise PC.
3. Using the external's Remote Desktop Connection, I remote into the virtual PC of #1.
4. Opening the Audio Devices of the virtual PC while remoting in, I can see "remote audio" for the playback device, but "no device is available" for the recording device.
5. I would like the remote recording device.
6. I have checked the RDP on both the virtual PC and external PC and they are of high enough version to support recording and playback redirection.
7. I have properly configured the Remote Desktop Connection of the external PC (I know because I can get this to work when I go external 1 -> external 2, but not external 1 -> virtual).

Is this a limitation of VMware, a setting issue, a permission issue?

Thanks,

Daniel