Why am I unable to use the ClearTrack command?

Ranger exposes the ClearTrack() method for those scanners that do support a track clearing functionality.

The Canon CR series scanners do not support such a functionality.

Your application can differentiate between scanners that do and don't support ClearTrack functionality by interrogating the TransportInfo.ini file. You'll notice that TransportInfo.ini indicates "UsesClearTrack=false" for all Canon devices.

Ranger^® - The universal check scanner interface