Getting started with SiRPAC

hi, 
I am just getting started with SiRPAC.  I have installed SiRPAC 1.14 on WinNT and I am using XML4J as well as SAX 2.  I think my classpath is set properly.  However, I got the error message like many people here had before, which is something like, "Exception in thread  "main" java.lang.ClassFormatError: org/w3c/rdf/SiRPAC (Illegal constant pool type)".  So I tried to recompile the SiRPAC.java file.  I then got another error message,
"SiRPAC.java:67: interface org.w3c.rdf.DataSource of Class org.w3c.rdf.SiRPAC not found.   ErrorHandler     DataSource{"
Does anyone come across this kind of things before?  What can I do then?  Thanks in advance!

Cecilia