I am encountering a error trying to activate IAudioEndpointVolume for a particilar device. I am pretty sure that m_pMMDevice refers to a valid device. But HRESULT hr = m_pMMDevice->Activate( __uuidof (IAudioEndpointVolume), CLSCTX_INPROC_SERVER, NULL, (void **)&m_pEndpointVolume); Is returning: hr 0x80070491 There was no match for the specified key in the index. HRESULT Can anyone explain what would cause this result? Andy ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/