MFRC522 RFID unknown version error solved

Hi,
i was having a lot of trouble lately getting my RFiD work with my arduino, It always showed an error "Unknown Version 0x02" so after diagnosing it for a complete day...i found two solution to it,
or i should say, two possible reason for this error

Solution_1: --> If you are using any kind of shield mounted on arduino, then remove that shield and rewire your RFiD with arduino Alone.

Solution_2: --> Change SDA default pin10 for rfid to some other pin which is not in use, Like pin 7 worked for me, and make this newly selected pin 7 "LOW" and pin10"HIGH" in "void setup()" function.

This worked for me, and 2 other of my friends
if still any problem persists, then ask for it

or directly email me at - iot.pranav@yahoo.in