API method available in JDK1.2.1 but not working in browser for servlet(internal server error 500)

I wrote a servlet that usede compareTo() method of java.util.Date class. In the documentation provided by sun it is mentioned that it is available since JDK 1.2. I am having JDK 1.2.1 anjd java web server 2.0 at my place.

The servlet compiled well. But when one applet called it in IE 5.0 browser it gave me internal server error: No such method found in (Ljava.util.Date)l. The messages were not so understandable. i don't know what is Ljava.

What should be done to use the available compareTo() method ?

Thanks for your help.