NFC Shield Seeeduino

Hi guys, I have 2 NFC Shields v2.1 from Seeeduino and I would like to send messagges from one to the other. I installed everything needed, and I have the two Arduino connected through two different usb ports of my Mac. I'm running the NDEF P2P_send and P2P_read script in two different releases of Arduino, so that I can have two serial monitors working. However, I'm not able to read anything. Can you guys help me troubleshoot this? I noticed that in the serial monitor of the sending part, I get the "send message" twice, then nothing:

NFCmple - Send Message Send a message to Peer NFC Peer to Peer Example - Send Message Send a message to Peer

Anyways, I'm attaching the code. Thanks for your help

// Sends a NDEF Message to a Peer
// Requires SPI. Tested with Seeed Studio NFC Shield v2

#include "SPI.h"
#include "PN532_SPI.h"
#include "snep.h"
#include "NdefMessage.h"

PN532_SPI pn532spi(SPI, 10);
SNEP nfc(pn532spi);
uint8_t ndefBuf[128];

void setup() {
    Serial.begin(9600);
    Serial.println("NFC Peer to Peer Example - Send Message");
}

void loop() {
    Serial.println("Send a message to Peer");
    
    NdefMessage message = NdefMessage();
    message.addUriRecord("http://shop.oreilly.com/product/mobile/0636920021193.do");
    //message.addUriRecord("http://arduino.cc");
    //message.addUriRecord("https://github.com/don/NDEF");

    
    int messageSize = message.getEncodedSize();
    if (messageSize > sizeof(ndefBuf)) {
        Serial.println("ndefBuf is too small");
        while (1) {
        }
    }

    message.encode(ndefBuf);
    if (0 >= nfc.write(ndefBuf, messageSize)) {
        Serial.println("Failed");
    } else {
        Serial.println("Success");
    }

    delay(3000);
}
// Receive a NDEF message from a Peer
// Requires SPI. Tested with Seeed Studio NFC Shield v2

#include "SPI.h"
#include "PN532_SPI.h"
#include "snep.h"
#include "NdefMessage.h"

PN532_SPI pn532spi(SPI, 10);
SNEP nfc(pn532spi);
uint8_t ndefBuf[128];

void setup() {
    Serial.begin(9600);
    Serial.println("NFC Peer to Peer Example - Receive Message");
}

void loop() {
    Serial.println("Waiting for message from Peer");
    int msgSize = nfc.read(ndefBuf, sizeof(ndefBuf));
    if (msgSize > 0) {
        NdefMessage msg  = NdefMessage(ndefBuf, msgSize);
        msg.print();
        Serial.println("\nSuccess");
    } else {
        Serial.println("Failed");
    }
    delay(3000);
}

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