Travel from South Korea to China

Hello

I would like to travel to visit the Great Wall from September 18-22, 2013. I am a US citizen currently working in South Korea with an ARC card. My ARC card is scheduled to expire 3.19.2014. I am being told that I may not be issued one because my ARC card must be valid for at least 6 months prior to travel. Can you please provide more details? I would like to book the trip but not if there is a chance I will not be issued it.

Thank you