It turns out that this is not an OSS/alsa issue, but a matter of whether /dev/mixer exists.
I tested the current program on my hardware with independent installs of OSS and alsa. In both cases, /dev/mixer was present and the program ran correctly.
Does this mean that alsa runs on your machine using a different device than /dev/mixer?
I guess that the info file will need updating to add that restriction.
Thanks for testing this.