can't get jde-help-docsets to work

[Nicholas Sushkin]

I have JDE 2.2.8 on Linux with emacs 20.7.1 and the following setting of
jde-help-docsets:

jde-help-docsets's value is
(("javadoc" "http://java.sun.com/j2se/1.3/docs/api"; nil)
 ("javadoc" "http://xml.apache.org/xalan-j/apidocs"; nil))

However, when I do

Alt-x jde-help-class org.xml.sax.Attributes

I get "Cannot find class org.xml.sax.Attributes on the current classpath."

org.xml.sax.Attributes is in my CLASSPATH, however.

How can I get this to work?

Thanks,

Nick