ESP8266 Httpclient get method works, but not with mfrc522

I have a problem with my ESP8266 that I really can understand. I am currently working on a security system which i have to use some RFID cards to manage the access on a door.

So i have create an C# web api + SQL database to manage the person and each RFID card.

The web api is basic, you just have to send at "http:///api/values/" and you will get "GO" or "Deny" if you are or not in the data base.

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>

const char* ssid = "yourNetworkName";
const char* password = "yourNetworkPassword";

void setup () {

  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {

    delay(1000);
    Serial.print("Connecting..");

  }

}

void loop() {

  if (WiFi.status() == WL_CONNECTED) { //Check WiFi connection status

    HTTPClient http;  //Declare an object of class HTTPClient

    http.begin("http://jsonplaceholder.typicode.com/users/1");  //Specify request destination
    int httpCode = http.GET();                                                                  //Send the request

    if (httpCode > 0) { //Check the returning code

      String payload = http.getString();   //Get the request response payload
      Serial.println(payload);                     //Print the response payload

    }

    http.end();   //Close connection

  }

  delay(30000);    //Send a request every 30 seconds

}

...But as soon as i added the RFID code... the request it will not work any more...

the code looks like this

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <SPI.h>
#include <MFRC522.h>

#define SS_PIN 5
#define RST_PIN 4

MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance.

const char* ssid = "mywifi";
const char* password = "Password";

void setup () {

  Serial.begin(9600);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {

    delay(1000);
    Serial.print("Connecting..");

  }
  SPI.begin();      // Initiate  SPI bus
  mfrc522.PCD_Init();   // Initiate MFRC522

}

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

  if (WiFi.status() == WL_CONNECTED) {
    //Check WiFi connection status

    HTTPClient http;  //Declare an object of class HTTPClient
    //http://<myip>/api/values/<cardCode>
    http.begin("http://<192.168.1.5>/api/values/1231");  //THIS IS A TEST, IT SHOULD WORK WITHOUT ANY PROBLEM!
    int httpCode = http.GET();                                                                  //Send the request

    if (httpCode > 0) { //Check the returning code

      String payload = http.getString();   //Get the request response payload
      Serial.println(payload);                     //Print the response payload

   [code] }

    http.end();   //Close connection

  }

delay(30000); //Send a request every 30 seconds

}

[/code]

The problem here is that my httpCode is return -1...and now response...

What i cannot understand is why...the ESP works...but without the MFRC522 library ?

Thank you in advance!

What i cannot understand is why...the ESP works...but without the MFRC522 library ?

What I can't understand is why the http.begin() calls specify two completely different values for the server/script. If you use the same server/script in the second code, does the GET succeed?

Is the same code for http.begin because it is an exemple... without the mfrc522 lib it works like a charm...but if you add this lib... ...the request isn't working anymore