The person who questioned you is correct. It's fake. I hope you can get a refund from the seller from whom you purchased. And the listing needs to be ended.I purchased this bag from ebay for my daughter, therefore, I assumed it was authentic. I have had someone question the authenticity so to be safe could you please authenticate. Thanks.
http://cgi.ebay.com/COACH-SIGNATURE...9?pt=US_CSA_MWA_Backpacks&hash=item3a608d7ce1
(Although you didn't ask, the mini skinny -- at least the box -- is questionable too.)