Newbie - Tomcat 5.0.28 Build failed (ExceptionInInitializerError)

[Raphael Damasceno]

Hi. I downloaded the Tomcat 5.0.28 source version and unzipped it, but when I ran Ant 
to build it, an ExceptionInInitializerError was thrown at this part of build.xml:
 
    <taskdef classname="org.apache.jasper.JspC" name="jasper2">
      <classpath refid="jspc.classpath"/>
    </taskdef>

Any suggestions? Thanks.
 
Raphael