problem in inserting data in database using asp.net

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

namespace WebApplication2
{
    public partial class WebForm7 : System.Web.UI.Page
    {
        
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
        {
            string pwd = args.Value;
            int l;
            l = pwd.Length;
            if (l >= 6 && l <= 8)
            {
                args.IsValid = true;
            }
            else
            {
                args.IsValid = false;
            }
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
             string name, gender, address, username, mobileno, email, password, cnfrmpassword;
            name = txtname.Text;
            address = txtaddr.Text;
            mobileno = txtmob.Text;
            username = TextBox4.Text;
            email = txtemail.Text;
            password = txtpass.Text;
            cnfrmpassword = txtconfirmpass.Text;
            gender = DropDownList2.SelectedItem.Text;
            SqlConnection con = new SqlConnection("Data Source=monikabishnoi\\sqlexpress;Initial Catalog=Signup;Integrated Security=True");
            SqlDataAdapter da = new SqlDataAdapter();
            da.InsertCommand = new SqlCommand("INSERT INTO Signup VALUES (@Name,@Gender,@Address,@Mobileno,@Username,@Email,@Password,@Cnfrmpassword");
            da.InsertCommand.Parameters.Add("@name", SqlDbType.NVarChar).Value = txtname.Text;
            da.InsertCommand.Parameters.Add("@gender", SqlDbType.NVarChar).Value = DropDownList2.Text;
            da.InsertCommand.Parameters.Add("@address", SqlDbType.NVarChar).Value = txtaddr.Text;
            da.InsertCommand.Parameters.Add("@mobileno", SqlDbType.NVarChar).Value = txtmob.Text;
            da.InsertCommand.Parameters.Add("@username", SqlDbType.NVarChar).Value= TextBox4.Text;
            da.InsertCommand.Parameters.Add("@email", SqlDbType.NVarChar).Value = txtemail.Text;
            da.InsertCommand.Parameters.Add("@password", SqlDbType.NVarChar).Value = txtpass.Text;
            da.InsertCommand.Parameters.Add("@cnfrmpassword", SqlDbType.NVarChar).Value = txtconfirmpass.Text;
            con.Open();
            da.InsertCommand.ExecuteNonQuery();
            con.Close();

        }
    }
}

name nvarchar(50)
gender nvarchar(50)
address nvarchar(50)
mobileno nvarchar(50)
username varchar(50)
email nvarchar(50)
password varchar(50)
cnfrmpassword varchar(50)