Display 7 seg and Shield RFID

Hi.

I´m using “#include <SevSeg.h>” library, and I show perfectly, when it is alone.

So, when I use a shield RFID (rfid-r522), by the code below, the display is blinking.

// Look for new cards
if ( ! mfrc522.PICC_IsNewCardPresent())
return;
// Select one of the cards
if ( ! mfrc522.PICC_ReadCardSerial())
return;

I would like show display in same time that the RFID reader is available for read a new card.

thanks

A conflict in the libraries is the most likely cause.