RFID-RC522

Hi! I'm trying to write to block 0 of my RFID card. I already now that most RFID cards doesn't have a changeable UID. I therefore bought a writeble card. The problem is that the RFID-reader doesn't read the card at all. I bought it here;

http://www.clonemykey.com/uid-changeable-mifare-1k-s50-classic-compatible-card-block-0-direct-write/

There is a good description of the card and it should be compatible. Why do you think it doesn't work? And how can I make it work?

The company does look like a serious one.