your Distribution is not correctly installed (or at least there's a bug with the dvb headers).
you can try to lower the API Version with following command:
/opt/bin/mediaclient --setver=5.0
and retry with w_scan, w_scan was packaged for the DVB API version 5.0, but our driver by default provides API support for the DVB API 5.1, it tries to detect lower versions which works with correct systems, for incorrect systems it can be set manually
what distribution do you use?
In case of tvheadend you can also ask in the tvheadend IRC channel on freenode.net where tvheadend developers and users give support to other tvheadend users we are watching it and try to help out too.