[opencms-dev] ClassNotFound Error : NewsContentDefinition

[elise.herichon-ext at powerconv.alstom.com]

Hello!
I must create an intranet site for a firm and I want to add a search engine
but I have a problem
Here is it : I downloaded and imported Lucene module
(net.grcomputing.opencms.search.lucene) and scheduled a task but I've an
error :
Error: com.opencms.core.CmsException: 0 Unknown exception. Detailed error:
Error instantiating class
com.opencms.modules.homepage.news.NewsContentDefinition.
root cause was java.lang.ClassNotFoundException:
com.opencms.modules.homepage.news.NewsContentDefinition
      at
net.grcomputing.opencms.search.lucene.SearchContentDefinition.<init>(Unknown
 Source)
      at
net.grcomputing.opencms.search.lucene.SearchParameters.readConfig(Unknown
Source)
      at
net.grcomputing.opencms.search.lucene.SearchParameters.<init>(Unknown
Source)
      at net.grcomputing.opencms.search.lucene.IndexManager.<init>(Unknown
Source)
      at
net.grcomputing.opencms.search.lucene.CronIndexManager.launch(Unknown
Source)
      at
com.opencms.core.CmsCronScheduleJob.run(CmsCronScheduleJob.java:68)

NewsContentDefinition class isn't provided with lucene. Where can I find
it? I need the .class because I can't compile the .java with Jbuilder.

Thanks and Regards

Liz