Arduino + LabView using LINX || collect2.exe: error: ld returned 1 exit status

[ITA]
Buonasera,

riporto l'errore che salta fuori ogni volta che provo a compilare un programma basato sul firmware fornito da LINX, col quale sto cercando di mettere in comunicazione Arduino + DHT22 e LabView.

Non sono un esperto per quanto riguarda questa tipologia di messaggi di errore, quindi mi rifaccio a voi, se avete qualche consiglio da darmi.

Grazie in anticipo e spero di non aver fatto qualche strafalcione con la scrittura di questo topic!

[ENG]
Good evening,

here are the error messages I get every time I try to compile a program I wrote. I'm using LINX firmware to make Arduino + DHT22 and LabView communicate.

I'm not really an expert about these error messages so I'm in your hands, if you have some advice.

Thank you very much!

Code and errors:

/**************************************************************************************** 
**  This is example LINX firmware for use with the Arduino Mega 2560 with the serial 
**  interface enabled.
**
**  For more information see:           www.labviewmakerhub.com/linx
**  For support visit the forums at:    www.labviewmakerhub.com/forums/linx
**  
**  Written By Sam Kristoff
**
**  BSD2 License.
****************************************************************************************/ 

#define DHTPIN 2
#define DHTTYPE DHT22

//Include All Peripheral Libraries Used By LINX
#include <SPI.h>
#include <Wire.h>
#include <EEPROM.h>
#include <Servo.h>
#include "DHT.h"

//Include Device Sepcific Header From Sketch>>Import Library (In This Case LinxArduinoMega2560.h)
//Also Include Desired LINX Listener From Sketch>>Import Library (In This Case LinxSerialListener.h)
#include <C:\Program Files (x86)\National Instruments\LabVIEW 2017\vi.lib\MakerHub\LINX\Firmware\Source\libraries\LinxArduinoMega2560\LinxArduinoMega2560.h>
#include <C:\Program Files (x86)\National Instruments\LabVIEW 2017\vi.lib\MakerHub\LINX\Firmware\Source\libraries\LinxSerialListener\LinxSerialListener.h>

//Create A Pointer To The LINX Device Object We Instantiate In Setup()
LinxArduinoMega2560* LinxDevice;

//**Forward declaration for the custom command function
int myCustomCommand_dht22();

//initialize dht22 and variables
DHT dht(DHTPIN, DHTTYPE);
float t, h;

//Initialize LINX Device And Listener
void setup()
{
  //Instantiate The LINX Device
  LinxDevice = new LinxArduinoMega2560();
  
  //The LINX Listener Is Pre Instantiated, Call Start And Pass A Pointer To The LINX Device And The UART Channel To Listen On
  LinxSerialConnection.Start(LinxDevice, 0);  

  //** Attach the custom command to the LINX Listener
  LinxSerialConnection.AttachCustomCommand(0,myCustomCommand_dht22);

  //**
  dht.begin(); 
}


void loop()
{
  //Listen For New Packets From LabVIEW
  LinxSerialConnection.CheckForCommands();
  
  //Your Code Here, But It will Slow Down The Connection With LabVIEW
}

//**
int myCustomCommand_dht22(unsigned char numInputBytes, unsigned char* input, unsigned char* numResponseBytes, unsigned char* response)
{
  unsigned char h = dht.readHumidity(); // Read RH value from sensor

  unsigned char t = dht.readTemperature(); // Read temperature as Celsius
  
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t)) {
    return 1;
  }
  response[0] = h;
  response[1] = t;

  *numResponseBytes = 2;

  return 0;

}
Arduino:1.8.3 (Windows 7), Scheda:"Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"

C:\Users\Lorenzo\AppData\Local\Temp\ccZrAcne.ltrans0.ltrans.o: In function `main':

ccZrAcne.ltrans0.o:(.text.startup+0x14a): undefined reference to `LinxArduinoMega2560::LinxArduinoMega2560()'

ccZrAcne.ltrans0.o:(.text.startup+0x15a): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x15c): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x15e): undefined reference to `LinxSerialListener::Start(LinxDevice*, unsigned char)'

ccZrAcne.ltrans0.o:(.text.startup+0x16a): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x16c): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x16e): undefined reference to `LinxListener::AttachCustomCommand(unsigned short, int (*)(unsigned char, unsigned char*, unsigned char*, unsigned char*))'

ccZrAcne.ltrans0.o:(.text.startup+0x196): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x198): undefined reference to `LinxSerialConnection'

ccZrAcne.ltrans0.o:(.text.startup+0x19a): undefined reference to `LinxSerialListener::CheckForCommands()'

collect2.exe: error: ld returned 1 exit status

exit status 1
Errore durante la compilazione per la scheda Arduino/Genuino Mega or Mega 2560.