Calling Java from a RPG program Class not found

Hi

I'm trying to get a program working that converts a file to Excel format 
which I found at:
http://www.jasservices.com/articles/as400/001_genexcel.htm

I downloaded the jar file from 
http://www.apache.org/dist/jakarta/poi/release/bin/ and put it
in directory /home/rah/lib/poi and then did an ADDENVVAR ENVVAR(JAVA_HOME) 
VALUE('/home/rah/lib/poi') 
and  ADDENVVAR ENVVAR(PATH) VALUE('/home/rah/lib/poi') 

The program still fails when I call it with:
Java exception received when calling Java method.
Java exception "java.lang.NoClassDefFoundError: 
org/apache/poi/hssf/usermodel/HSSFWorkbook" when calling method "<init>" 
with signature "()V" in class "org.apache.poi.hssf.usermodel.HSSFWorkbook"

I can look at the jar file in WinZip and I find the class and the path 
mentioned in the message.
Something's wrong with my jobs environment but I don't know what.
Anyone have an idea what I need to do to get this work?

Thank You
Ron