please fix this issue, my code gives me this error from this line

Line: cmd.ExecuteNonQuery();
Error: System.Data.OleDb.OleDbException: 'No value given for one or more required parameters.'

Full code:
using System;
using System.Linq;
using System.Data.OleDb;
using System.Windows.Forms;
using System.Drawing;
using static System.Net.Mime.MediaTypeNames;

namespace ApplianceRental
{
    public partial class RegistrationForm : Form
    {
        // Declare and initialize a new OleDbConnection object
        private readonly OleDbConnection connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db_users.mdb");

        public RegistrationForm()
        {
            // Initialize UI components
            InitializeComponent();
        }
        
       
        private void Register_Click(object sender, EventArgs e)
        {
            // Check for an empty username box
            if (string.IsNullOrEmpty(textBox1.Text))
            {
                MessageBox.Show("Please enter a username.");
                return;
            }

            // Check for an empty password box
            if (string.IsNullOrEmpty(textBox2.Text))
            {
                MessageBox.Show("Please enter a password.");
                return;
            }

            // Compare password boxes for a match
            if (textBox2.Text != textBox3.Text)
            {
                MessageBox.Show("Passwords do not match.");
                return;
            }

            // Check for an empty full name box
            if (string.IsNullOrEmpty(textBox4.Text))
            {
                MessageBox.Show("Please enter your full name.");
                return;
            }

            // Check for an empty email address box
            if (string.IsNullOrEmpty(textBox5.Text))
            {
                MessageBox.Show("Please enter your email address.");
                return;
            }

            // Check for an empty address box
            if (string.IsNullOrEmpty(textBox6.Text))
            {
                MessageBox.Show("Please enter your address.");
                return;
            }

            // Check for valid password length
            if (textBox2.Text.Length < 8 || textBox2.Text.Length > 16)
            {
                MessageBox.Show("Password must be between 8 and 16 characters.");
                return;
            }

            // Check for presence of both lowercase and uppercase characters
            if (!textBox2.Text.Any(char.IsLower) || !textBox2.Text.Any(char.IsUpper))
            {
                MessageBox.Show("Password must contain at least one lowercase and one uppercase letter.");
                return;
            }

            // Open the database connection
            try
            {
                connection.Open();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error connecting to the database: " + ex.Message);
                return;
            }

            // Insert the user’s registration data into the database
            
                using (var cmd = new OleDbCommand())
                {
                    cmd.Connection = connection;
                    cmd.CommandText = "INSERT INTO tbl_users(username, [password], fullname, email, address, [User Type]) " +
                    "VALUES(@username, @password, @fullname, @email, @address, ‘Customer’)";

                    cmd.Parameters.AddWithValue("@username", textBox1.Text);
                    cmd.Parameters.AddWithValue("@password", textBox2.Text);
                    cmd.Parameters.AddWithValue("@fullname", textBox4.Text);
                    cmd.Parameters.AddWithValue("@email", textBox5.Text);
                    cmd.Parameters.AddWithValue("@address", textBox6.Text);

                    cmd.ExecuteNonQuery();
                }
            
                // Close the database connection
                connection.Close();
            

            // Inform the user that the registration was successful
            MessageBox.Show("Registration successful!");

            // Clear input fields
            ClearFields();

            // Hide this form and show the main form
            this.Hide();
            new Form1().Show();
        }
        
        // Clear input fields
        private void ClearFields()
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            textBox5.Text = "";
            textBox6.Text = "";
        }

        // Event handlers for text-changed events (placeholders)
        private void textBox1_TextChanged(object sender, EventArgs e) { }
        private void textBox2_TextChanged(object sender, EventArgs e) { }
        private void textBox3_TextChanged(object sender, EventArgs e) { }
        private void textBox4_TextChanged(object sender, EventArgs e) { }
        private void textBox5_TextChanged(object sender, EventArgs e) { }
        private void textBox6_TextChanged(object sender, EventArgs e) { }
    }
}