Ok... I've posted the demo code to my web site.
Default.aspx and Default2.aspx show the themes and master pages.
Default3.aspx shows the "Automation" part where you can select a theme from a drop down list box and it will automatically change.
Now... if someone can take a look at Default.aspx and tell me why it doesn't work I'll post the answer. I can't find anything wrong with it, but it sure doesn't work. The only difference between it and Default3.aspx is the fact that it is using a Master page. I just copied the control and the code to Default3.aspx and it worked.
I'll post the answer here when I get it.
Thanks for watching!!!