Can't read cards from RFID RC522

I am using RC 522 RFID Module and MFRC 522 library to read cards and tags.when i uploaded the example comes within library Dumpinfo i am getting following message on the serial monitor:

"Firmware Version: 0x0 = (unknown)
WARNING: Communication failure, is the MFRC522 properly connected?
Scan PICC to see UID, SAK, type, and data blocks..."

Can anybody please help me with this?

all pins connected? (except IRQ)
Ucc=3v3 ?
Select correct library.. I2C vs SPI