The only one who can help you is OP, but he is not active anymore in this forum (more than a month). The other way to ask is send them an email to admin@coincheckin.com, but not really sure you'll get any replies or not. As I see on the payout page, last payout was May 20th 2015. Seems that the site is not paying anymore or no body play here.

P.S : You are not the only one who get minus balance, I checked my own account and I got the same but only -4k satoshi. http://prntscr.com/7sgrg7