SQL differtail backups

I have a customer that we have upgraded to BE 2012 SP3.

I need to be able to do a full backup of a SQL DB on the weekends and differential during the week.

From what I read it is possible.

Right now the full runs fine and when the incremental runs the error says the last full backup of said DB was not made by this application run a new full backup?   Just the day before this error a full ran 100% successfully.

When you click on the backup options then the Microsoft SQL part ti tells you have to have a log backup and a second one that says differentail in the mothod.  I set those up and it did not help.

So what am I missing?

Thanks

Mike