Does not read information by serial port when creating executable

COULD SOMEBODY PLEASE HELP ME? I'M MAKING A GAME THAT RECEIVES INPUT FROM AN ARDUINO BOARD THROUGH SERIAL PORT. EVERYTHING WORKS FINE DURING TESTS BUT ONCE I MAKE THE EXECUTABLE FILE THE GAME DOES NOT RESPOND TO THE IMPUTS FROM ARDUINO.

this is my code and I just added it to an object in my scene.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.IO.Ports;
 using System.ComponentModel;
 
 public class Arduino : MonoBehaviour
 {
     public SerialPort stream = new SerialPort();
     public string Pendant;
     //*********Nuevas*********//
     public CilindroViga MovCilindroViga;
     public Movimiento_Transversal Movtransversal;
     public CilindroBrazo MovCilindroBrazo;
     public Tijera_Arriba MovTijera;
     public Inclinacion MovTilt;
     public Tijera_acercar MovPlataforma;
 
     void Start()
     {
         //*********Nuevas*********//
         MovCilindroViga = GameObject.Find("Palanca4").GetComponent<CilindroViga>();
         Movtransversal = GameObject.Find("Palanca7").GetComponent<Movimiento_Transversal>();
         MovCilindroBrazo = GameObject.Find("Palanca5").GetComponent<CilindroBrazo>();
         MovTijera = GameObject.Find("Palanca8").GetComponent<Tijera_Arriba>();
         MovTilt = GameObject.Find("Palanca9").GetComponent<Inclinacion>();
 
         stream.PortName = "COM3";
         stream.BaudRate = 9600;
         stream.Parity = Parity.None;
         stream.StopBits = StopBits.One;
         stream.DataBits = 8;
         stream.Handshake = Handshake.None;
         stream.RtsEnable = true;
         stream.Open();
         int readt = 1;
         stream.ReadTimeout = readt;
     }
 
     void Update()
     {
         try
         {
             Pendant = null;
 
             if (stream.ReadLine() != null && stream.IsOpen)
             {
                 Pendant = stream.ReadLine();
             }
         }
         catch (System.TimeoutException)
         {
 
         }
         switch (Pendant)
         {
             //---Cilindro Viga (Drill Crowd)---
             case "J1":
                 MovCilindroViga.RapidoPalancaArriba();
                 break;
             case "J2":
                 MovCilindroViga.RapidoPalancaAbajo();
                 break;
             //---Transversal---SI
             case "K1":
                 Movtransversal.RapidoPalancaArriba();
                 break;
             case "K2":
                 Movtransversal.RapidoPalancaAbajo();
                 break;
             //---Cilincro Brazo (Boom Crowd)---SI
             case "L1":
                 MovCilindroBrazo.RapidoPalancaArriba();
                 break;
             case "L2":
                 MovCilindroBrazo.RapidoPalancaArriba();
                 break;
             // ---Rollover---SI
             case "M1":
                 MovRollover.RapidoPalancaArriba();
                 break;
             case "M2":
                 MovRollover.RapidoPalancaAbajo();
                 break;
             // ---Tijera---SI
             case "N1":
                 MovTijera.RapidoPalancaArriba();
                 break;
             case "N2":
                 MovTijera.RapidoPalancaAbajo();
                 break;
             //---Tilt---SI
             case "O1":
                 MovTilt.RapidoPalancaAbajo();
                 break;
             case "O2":
                 MovTilt.RapidoPalancaArriba();
                 break;
         }   
     }
 }