My Passport external drive won't backup

I’ve been having this problem off and on ever since these drives (I have two) were new. When I try to run a back-up, either scheduled or on the spot, it just won’t run. I get a message “Backup was completely successfully”. I used to be able to “fool” it by switching from a category-type of backup to a file-type. But now, that doesn’t work either. I’m about ready to dump these and switch to another brand. BTW, I have kept the software up to date.

Anyone have any ideas?

If you have no new files to add then WD SmartWare will report the backup as completed within seconds. It keeps a single, continuous gradual backup and does not start over.