Control child of server control won't set an event

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C#

ASP.NET

server-control

Hi all,
I have server control and it has a child control in it. The problem is I want to set an event to that control but it dosn't riase :(

protected override void RenderContents(HtmlTextWriter output)
        {
            TextBox txtBox = new TextBox();
            txtBox.ID = "txtBox";
            txtBox.AutoPostBack = true;
            txtBox.TextChanged += new EventHandler(txtBox_TextChanged);
            txtBox.RenderControl(output);
        }
        protected void txtBox_TextChanged(object sender, EventArgs e)
        {

        }

When I write some text in the textbox and press tab (which must raise the event textchanged) the page dosn't reload and the event dosn't raise.
When I view the source code of the page in the browser I only find this:

<input id="txtBox" type="text" name="txtBox"></input>

Why I can't find onclick or something like that????!!!
Why textchanged event dosn't raise???!!!!!