Product review (5 stars): Don't Give Up, They Will Fit
I almost returned these since the threading on the top didn't look the same as the old filter.  Apparently, all manufacturers have changed the threading style.  What you have to do is push the filter up firmly, and then twist.  I had to push pretty hard to get it to click into place, then just turned it easily to screw it in place.  These are great filters, don't give up on installation, try again.