Can' t open mixer default (Hauppage HVR-950Q)

When running TVtime, the following errors appear in the console:

mixer: Can't open mixer default, mixer volume and mute unavailable.
mixer: Can't open device default/Line, mixer volume and mute unavailable.

As a workaround, one can check what devices are available:

cat /proc/asound/cards ubuntu-bug tvtime
 0 [Intel ]: HDA-Intel - HDA Intel
                      HDA Intel at 0xf7cf4000 irq 48
 1 [HVR950Q ]: USB-Audio - HVR-950Q
                      Hauppauge HVR-950Q at usb-0000:00:1a.0-1.2, high speed

And modify /etc/tvtime/tvtime.xml accordingly:

<!--
   <option name="MixerDevice" value="default/Line"/>
-->
   <option name="MixerDevice" value="hw:0/Line"/>

This may be related to bug #613809.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: tvtime 1.0.2-7ubuntu9
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
CasperVersion: 1.315
Date: Sun Apr 29 14:10:15 2012
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: tvtime
UpgradeStatus: No upgrade log present (probably fresh install)