Well, I think the error says for itself. What raspberry module version are you using? Can you show your code? I believe in most cases, the problem lies on your file structures. Read this from "github ("")":https://github.com/metachris/RPIO/issues/53 though, it might help.
Iam agree with you kevin. In almost all cases the problem will associated with the file structures. If you want to communicate with MIFARE Classic cards you need a NFC reader which fulfill specifications for this card. Read this article UHF band RFID Reader for more info
