If the Java Plugin is not installed or enabled the applet would not run in the Internet Explorer as seen the screen shot below.
In order to enable Java in Internet Explorer, perform the following steps.
1. From the Tools menu, or the Tools drop-down in the upper right corner of IE, select Internet options menu.
2. Click the Programs tab, and then click Manage Add-ons.
3. Highlight Java Plug-in that you have installed, could be Sun or IBM or some other implementation.
* If you don’t find the Java Plugin Addon, that means the Plugin as not been installed, so go ahead and install it.
4. Click Disable or Enable the Java Plugin Addon as required as show below.
5. Close your browser and restart it and see if applets start to work.