how to set roles in c# windows application

hi all,

 am doing the roles management in  login page using c# windows application.

actually i have done the code but which was working partially in my code,

i have two table the name is,

1.adminlogin

2.userlogin.

my problem is when i have enter username and password  whether its  from adminlogin or userlogin whatever it is, i need to log in but in my code has doing  only one side of table. that is nothing but the else if statement.

so please have a look into it  my code below and tell me where i did mistake..

my code is:

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Data.SqlClient;
using System.Data;
using System.Windows.Forms;



namespace WindowsApplication1
{
    public partial class test : Form
    {
        SqlDataAdapter da;
        DataSet ds = new DataSet();
        DataTable dt = null;
        DataRowCollection dr = null;
        //DataRow dr1=null;
        SqlConnection xconn = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=test;User ID=sa;Password=sa");
        public test()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            if (txtLoginName.Text == "" || pbPassword.Text  == "")
            {
               // MessageBox.Show("Login name or password cannot be left blank", "Invalid Login Information", this.Text, MessageBoxButton.OK, MessageBoxImage.Information);

                MessageBox.Show("Login name or password cannot be left blank", "Invalid Login Information",MessageBoxButtons.OK);
                
                txtLoginName.Focus();
            }
            
            if (txtLoginName.Text == "Administrator")// checking whether the user is an administrator or not
            {
                string loginname = null;
                string password = null;
                da = new SqlDataAdapter("select * from adminlogin", xconn);
                da.Fill(ds, "adminlogin");
                dt = ds.Tables["adminlogin"];
                dr = dt.Rows;
                //dr1 = dr[0];
                loginname = dr[0][0].ToString();
                password = dr[0][1].ToString();
              
                if (txtLoginName.Text == loginname && pbPassword.Text == password)
                {
                    Form2  obj = new Form2 ();// showing the Admin form
                    MessageBox.Show("Welcome Administrator");
                    this.Hide();
                    obj.Show();
                }


                else
                {
                    MessageBox.Show("The username and/or password entered is wrong", "Invalid admin credentials");
                    pbPassword.Text = "";
                    pbPassword.Focus();
                }
                
            }




            else if (txtLoginName.Text != "Administrator")// if the user is not an administrator
            {
                da = new SqlDataAdapter("select * from userlogin", xconn);
                ds.Clear();
                da.Fill(ds, "userlogin");
                dt = ds.Tables["userlogin"];
                dr = dt.Rows;

                string userlogin = null;
                string userpassword = null;
                SqlCommand comm = new SqlCommand("select count(*) from userlogin", xconn);
                xconn.Open();
                int value = Convert.ToInt32(comm.ExecuteScalar());
                xconn.Close();
                //MessageBox.Show("number =" + value);
                for (int i = 0; i <= value - 1; i++)
                {
                    userlogin = dr[i][0].ToString();
                    userpassword = dr[i][0].ToString();
                    if (txtLoginName.Text == userlogin && pbPassword.Text == userpassword)
                    {
                        Form1  obj1 = new Form1 ();// Showing the normal user form
                        MessageBox.Show("Welcome user:" + userlogin);
                        this.Hide();
                        obj1.Show();
                    }
                }
            }
            else
            {

                MessageBox.Show("The username or password entered is incorrect", "Invalid user credentials");
                txtLoginName.Text = "";
                pbPassword.Text = "";
                txtLoginName.Focus();
            }
        }
    }
}

thanks in advance..