A lot of partners are having issues posting the exact Facebook post link on the contest page. The screen shot below will show you the steps you need to take to grab and post your facebook link.
On your facebook page, click on the date you shared the link as shown on the image below.
That will bring you to a page as shown on the screenshot below. Copy the url and paste it on the box provided for links. Thats it
I hope this was helpful. Good luck to you all as you go about wining the contest.