if you have the "nut" on there to tight it will not spin which will cause it to not cut. Loosen up the nut so the blade spins freely but doesn't fall off and try cutting fabric! My fiskar tends to get loose and I have to tighten it but I know I can't tighten it TO tight or it won't work!
With a new/sharp blade you should be able to cut at least three or four layers, I know with a sharp blade while working on my sisters quilt I was cutting about six at once!