That pool has closed its signups in order to help spread the network hash.  

Just sign up at one of the other pools:
http://drkpool.com/
https://www2.coinmine.pl/drk/
http://cpu-pool.net/drk/
http://drk.lotterymining.com
http://drk.smalltimeminer.com
http://drk.yobapool.net/