Why is EventHandler not triggered in the following asp.net code?

IDE: Visual Studio 2010

.net version: 3.5

OS: Windows 7

Web Server: Visual Studio 2010 Development Server

Below is the asp.net C # code. This is the code behind an otherwise empty, out of the box, web form. I don't understand why the testClick event doesn't fire when I click on the button, but if I comment out the next line so that the button is made on the back, it fires.

if (!IsPostBack)

      

        
        
        
      

    

Obviously it has to do with the page lifecycle and how / when the controls are rendered, but I don't understand. When the page returns, isn't the btnTest button a new instance of btnTest? Why does the page care if it actually exists after the postback? An event handler exists. It seems like it should be important. I hope someone can break the order in which everything happens and explain this (clearly correct and intentional) behavior for me.

Thanks for reading.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page 
{
    Button btnTest = new Button();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            btnTest.Text = "TEST";
            this.Form.Controls.Add(btnTest);
            btnTest.Click += new EventHandler(testClick);
        }
    }

    protected void testClick(Object sender, EventArgs e)
    {
        Response.Write("Test button event has been handled");
    }
}

      

        
        
        
      

    

Ok, now I'm TOTALLY confused! In the following code, btnTest and btnTest2 are not the same button. When the page returns messages, it fires an event handler for btnTest2, as if btnTest2 was pressed but btnTest2 was not pressed. btnTest was. I don't understand this behavior. I have read the page Lifecycle article at https://msdn.microsoft.com/en-us/library/ms178472(v=vs.80).aspx as suggested, but I don't think it adequately explains this behavior.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Button btnTest = new Button();
            btnTest.Text = "TEST";
            this.Form.Controls.Add(btnTest);
            btnTest.Click += new EventHandler(testClick);
        }       

        if (IsPostBack)
        {
            Button btnTest2 = new Button();
            btnTest2.Text = "TEST";
            this.Form.Controls.Add(btnTest2);
            btnTest2.Click += new EventHandler(testClick_Postback);
        }        
    }

    protected void testClick(Object sender, EventArgs e)
    {
        Response.Write("Test button event has been handled by original handler");
    }

    protected void testClick_Postback(Object sender, EventArgs e)
    {
        Response.Write("Test button event was handled by new handler assigned on postback");
    }
}