Folders not fully synchronizing

I am using True Image 2013 (purchased version) on Win 8 and setting up sync folders between an internal hard drive and an external backup (2T with plenty of empty space). I have set up a number of folders and keep getting sync errors and am also finding that in some instances only part of the folder contents is being backed up to the external drive. I have tried removing and recreating the syncs but it hasn't made any difference. Do I need to actually remove the folder on the external drive and create a new one with a sync that starts from scratch? It's very annoying getting the constant message (in another sync pair) 'synchronization has failed". Anyone have any suggestions?
Thank you