How do you make your fondant ruffles?????
I don't put corn syrup into my crusting icing and have never had a problem with the ruffles falling off, but I'd also agree that your buttercream looks like it was too dry.
Here's a tutorial on doing the ruffles with the fondant, it isn't hard. I've done a bunch of ruffle cakes and always put the fondant ruffles onto buttercream cakes with no problems, too. At the bottom of the tutorial comments is another link to an article about how to do ruffles with buttercream. Just make sure your icing is smooth enough to pipe wihtout getting a raggedy looking edge and it should work fine. http://acaketorememberva.blogspot.com/2011/11/ruffle-wedding-cake-tutorial.html