Redirect based on User Role using C# in ASP.Net

How do I login based on user role? This is my C# code but its not working

Server side Code:

    protected void Button1_Click(object sender, EventArgs e)
    {
        if (txtUsername.Text != "" & txtPassword.Text != "")
        {
            string check = "select count(*) from [Users] where email = '" + txtUsername.Text + "' and pass = '" + txtPassword.Text + "'";
            SqlCommand com = new SqlCommand(check, con);
            con.Open();
            int temp = Convert.ToInt32(com.ExecuteScalar().ToString());
            con.Close();

            if (temp == 1)
            {
                string user = txtUsername.Text.Trim();
                com.CommandText = "select * from Users where email='" + txtUsername.Text + "'";
                com.Connection = con;
                sda.SelectCommand = com;
                sda.Fill(ds, "detail");
                if (ds.Tables[0].Rows.Count > 0)
                {
                    string UserRole;
                    UserRole = dt.Rows[0][4].ToString().Trim();

                    if (UserRole == "U")
                    {
                        Session["user"] = user;
                        txtUsername.Text = "";
                        txtPassword.Text = "";
                        Response.Redirect("UsersHome.aspx");
                    }
                    if (UserRole == "A")
                    {
                        Session["user"] = user;
                        txtUsername.Text = "";
                        txtPassword.Text = "";
                        Response.Redirect("Home.aspx");
                    }
                }

            }