Incremental backup will NOT increment -- Always full backup.

I need a solution Win 7-64 SSR 2013 11.0.2.49853 up to date. 

I have an internal HD that I have a backup job to a FOLDER on drive "N". I am attempting to run incremental backup of an external USB drive to a different folder also on drive N.  I can not get the incremental back up to increment.  I ALWAYS get a new full backup set. The full-incremental backup is been indexed by one such as -002.v2i and -003.v2i each time.

Is the reason:

I am backing up from an external USB drive.  SSR does not write the VtrackDiskController or the .VTrack folder to the external disk.

Or is the problem that I am trying to use folders not partitions on the HD I store the backup.