No such property: com for class: embedded_script...

Hi,

when trying to run any webtest (also the provided simple examples), the
tests seem to work but then i get the following error message:

[echo] Waiting for completion of background generation of single erports

BUILD FAILED
..\webtest.xml:299: groovy.lang.MissingPropertyException: No such
property: com for class: embedded_script_in_C_....

Line 299 in webtest.xml is:  

<groovyScript description="Wait for termination of the single report
generation">
  <![CDATA[			
    com.canoo.webtest.reporting.HTMLReportGenerator.shutdown()
  ]]>
</groovyScript>

Any ideas?

Thanks in advance, 

Raphael