<p align="center">
<applet code="MainClass.class" width="640" height="640" alt="Applet GUIDemo demonstrates some basic GUI components">
<div align="center">
<p>
<b>Java is not enabled in your browser</b>
</applet></p>
1. I know this code is XHTML wrong, but I don't use XHTML;
2. The problem is probably the class file;
3. This works great for me (with functional applets classes) so try it too.