My namespace disappear in ASP. NET 2 (beta2 )?

When you create your first ASP. NET 2.0 web page. You may say: "Oh! ", There's no default namespace in your code-behind CS file? OK, let's add one, we think every object shocould be in one certain namespace. it's easy to add it, and then let's press F5 to run it. "what? Errors? I didn't do anything! Just add a namespace! ".
OK, calm down, let me explain it. When you add a namspace to you Aspx. CS file. Please turn to the corresponding aspx file. Look at this:
<% @ Page Language = "C #" autoeventwireup = "true" codefile = "default. aspx. cs" inherits = "_ default" %>
You see, current page is inherited from the _ default, it shocould be changed to mynamespace. _ default, right? Add it, and press F5, OK, you got it, you first page run successfully! Congratulation!
There're so far different things between ASP. NET 1.1 and 2.0. I'm sure, and I'm a beginner. Anyway, let's learn these things one by one.