Can't read repository file 'repository.xml

Hi all,
I am getting an error while trying to retrieve my repository.xml file. 
My repository.xml is under the WEB-INF/classes directory of my struts 
web application.
Exactly the line is where i try to read it is:

PBKey pbKey = new PBKey("repository.xml");

I tried with relative url-path:

PBKey pbKey = new PBKey("/WEB-INF/classes/repository.xml");

and local disk path:

PBKey pbKey = new 
PBKey("/home/user/web_app/WEB-INF/classes/repository.xml");

but without success.  Nothing comes in catalina.out and i do not have 
any idea where can be the problem. If anyone can point me to a solution, 
it would be great. Here is the error:

HTTP Status 500 -
------------------------------------------------------------------------
*type* Exception report
*message*
*description* _The server encountered an internal error () that 
prevented it from fulfilling this request._
*exception*
javax.servlet.ServletException: Can't read repository file 'repository.xml'
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:535)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:433)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
*root cause*
org.apache.ojb.broker.metadata.MetadataException: Can't read repository 
file 'repository.xml'
org.apache.ojb.broker.metadata.MetadataManager.init(Unknown Source)
org.apache.ojb.broker.metadata.MetadataManager.<init>(Unknown Source)
org.apache.ojb.broker.metadata.MetadataManager.getInstance(Unknown Source)
org.apache.ojb.broker.query.QueryFactory.getRepository(Unknown Source)
org.apache.ojb.broker.query.QueryFactory.newQuery(Unknown Source)
org.apache.ojb.broker.query.QueryFactory.newQuery(Unknown Source)
com.softamo.libamo.about.dao.AboutDAO.findAllAbout(AboutDAO.java:209)
com.softamo.libamo.struts.about.AboutPageAction.execute(AboutPageAction.java:30)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
*note* _The full stack trace of the root cause is available in the 
Apache Tomcat/5.5.17 logs._
------------------------------------------------------------------------
Apache Tomcat/5.5.17

thanks in advanced for your feeback,
Sergio del Amo