There are fewer columns in the INSERT statement than values specified in the VALUES clause

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

public partial class Registration : System.Web.UI.Page
{
    SqlDataAdapter da;
    DataSet ds;

    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["shop02ConnectionString"].ConnectionString);
    protected void Page_Load(object sender, EventArgs e)
    {

        if (con.State == ConnectionState.Closed)
        {
            con.Open();
        }
        
    }
    
    protected void Button1_Click1(object sender, EventArgs e)
    {
        da = new SqlDataAdapter("insert into shop02 ( firstname, lastname, gender,email,city, state,country, mobile) values('"+TextBox1.Text+"','"+TextBox2.Text+"','"+TextBox3.Text+"','"+TextBox3.Text+"', '"+TextBox4.Text+"','"+TextBox5.Text+"', '"+TextBox6.Text+"', '"+TextBox7.Text+"', '"+TextBox8.Text+"')", con);
        da.SelectCommand.ExecuteNonQuery();


    }
    protected void TextBox1_TextChanged(object sender, EventArgs e)
    {
        da = new SqlDataAdapter("select count(firstname) from shop02  where firstname = '" + TextBox1.Text + "'", con);
        ds = new DataSet();
        da.Fill(ds, "regis");
        if (ds.Tables["regis"].Rows.Count == 1 && ds.Tables["regis"].Rows[0][0] == "1")
        {
            Label9.Text = "firstname not ava";
            Label9.BackColor = System.Drawing.Color.Azure;
        }

     }
}



and table is..
 id int identity(1,1) primary key,
  firstname varchar(88),
  lastname varchar(88),
  gender varchar(88),
  email varchar(88),
  city varchar(88),
  state varchar(88),
  country varchar(88),
  mobile varchar(88)