Problem with Xalan2.7.0 transformation

Hi All
          I am using Xalan2.7.0 for my transformations. I have registered a
errorlistener for transformer factory and transformer objects. For any xsl
validation errors i am able to catch them by the use of error listner. Now
the issue is in case of transformation exceptions say i use a extension
function and that java class is not is not in classpath then there is
exception printed in console but no exception is thrown. How can i handle
these transformtion time exceptions.

Thanks in Advance for any help.
Pankaj