Samsung has upgraded the Galaxy S 4′s NFC chipset in a way that it no longer communicates with older Samsung NFC tags called TecTiles. When asked about this problem Samsung had this to say:
Samsung is introducing TecTile 2, an update to the original TecTile NFC programmable tags, which will be available in the coming weeks. TecTile 2 will use the current NFC technology on the market, allowing Samsung customers to further incorporate NFC into their daily lives and to use with the latest Samsung Mobile products and services, including the Galaxy S 4. As industry standards continue to evolve, Samsung remains committed to meeting those standards and adapting its technologies if necessary. Samsung customers can also fully utilize TecTiles 2 with existing Samsung Mobile NFC-enabled Android smartphones currently in market.