How to receive data from the RS232 serial port

I need to receive data from a scale, I have already managed to send data but I cannot receive the data from the scale that is connected by RS232. How can I connect to this scale that shows me the weight on a Label? How could I connect this balance?

This code helps me to communicate with the com but I do not receive anything from the scale:

Code

 public partial class FormInicio : Form
    {
        public FormInicio()
        {
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;
        }
        private void puertosDisponibles()
        {
            foreach (string puertoDis in System.IO.Ports.SerialPort.GetPortNames())
            {
                cmbPuertos.Items.Add(puertoDis);
            }
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            puertosDisponibles();
        }
        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            serialPort1.Close();
        }
        private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            string datorx=serialPort1.ReadExisting();
            txtRx.Text = datorx.Trim();
        }
        private void cmbPuertos_SelectedIndexChanged_1(object sender, EventArgs e)
        {
            serialPort1.PortName = cmbPuertos.Text;
            cmbPuertos.Enabled = false;
            try
            {
                serialPort1.Open();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Selecciones otro puerto", "Puerto no disponible");
                cmbPuertos.Enabled = true;
            }
        }
        private void btnEnviar_Click_1(object sender, EventArgs e)
        {
            try
            {
                serialPort1.Write(txtTx.Text.Trim());
                txtTx.Clear();
            }
            catch (Exception ex)
            {
                MessageBox.Show("No se puedo enviar la información", "Error", MessageBoxButtons.OK,
                MessageBoxIcon.Error);
            }
        }

    }
}

I have the following code that I call in a textBox, but I can't get anything. What am I doing wrong or how could I display the scale data?

SerialPort spPuertoSerie = new SerialPort();
spPuertoSerie.PortName = "COM1";
spPuertoSerie.Handshake = Handshake.None;
spPuertoSerie.BaudRate = 9600;
spPuertoSerie.Parity = Parity.None;
spPuertoSerie.StopBits = StopBits.One;
spPuertoSerie.DataBits = 8;