Getting text from a Textbox

Hi I am trying to get some text from a textbox using C# and ASP but it seems to come up as nothing everything. I am getting an Object reference not set errors in my cs file where i defined string st.... Any ideas?

my aspx code is:login.aspx


           
               

                   
               

               

                   

Log in Form

                   

                       
1. 
                               User name
                              
                              
                          

                       
2. 
                               Password
                              
                              
                          

                       
3. 
                              
                               Remember me?
                          

                   

                   
               

           
       

My login.aspx.cs code is :

 protected void Unnamed6_Click(object sender, EventArgs e)
        {
           
            //TextBox User_N = (TextBox)this.FindControl("UserName");
            //TextBox User_P = (TextBox)this.FindControl("Password");

            OleDbConnection connect = new OleDbConnection();
            connect.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Diary Model_CurrentBuild.mdb;Persist Security Info=False;";
            connect.Open();
            // string sqlstring = "Insert
            OleDbCommand command = new OleDbCommand();
            command.Connection = connect;
           // string a = Convert.ToString(this.FindControl("UserName"));
           
            TextBox box = (TextBox)this.FindControl("UserName");
            string st = box.Text;
            command.CommandText = "Select * from STAFF where staffName = '" + st + "' OR password = '" + this.FindControl("Password") + "'";
            OleDbDataReader reader = command.ExecuteReader();
           
            if (reader.Read())
            {
                Response.Redirect("../Default.aspx");
            }

           
            connect.Close();


        }