Hi Dave,
I have the exact same question...
I even tried to rebuild the dll but this does not seem to work either.
Are you testing it with ArcGIS for Windows Mobile 3.0 or like me with ArcGIS for Windows Mobile 3.1 or 10.1.1 ?
Maybe this is a compatibility issue ?
Hope ESRI can give us some tips, because this data collection extension is worth it...
Regards
Julien