Buttonholer on Simplicity S180?

After successfully completing a few good buttonholes, the machine just continues the back bar tack rather than switching back to the narrow stitch & returning to the front. What might be the problem?
This machine has a buttonhole foot into which the button is placed so the machine knows what size to make the buttonhole, and a place on the stitch dial to designate buttonhole. It also has a reset position, which must be turned before making another buttonhole.
I spent quite a bit of time figuring out how to make it work, then after about 4 successes, I am unable to make it work any more.