Java Programming

Hi
I am using, jdk 1.5 in windows, oracle 10g, tomcat 5.x with cocoon-2.0.4.jar . I have set classpath for ojdbc14.jar in my local system env also added in eclipse.

when i run the application i am getting folowing error:

Original exception : java.lang.RuntimeException: Could not get the datasource java.lang.NullPointerException 
at org.apache.cocoon.www.xsp.index_xsp.generate(C:\programs\Tomcat-5.0\work\Catalina\localhost\epub\cocoon-files\org/apache/cocoon/www/xsp\index_xsp.java:350) 
at org.apache.cocoon.generation.ServerPagesGenerator.generate(ServerPagesGenerator.java:258) 
at org.apache.cocoon.components.pipeline.CachingEventPipeline.process(CachingEventPipeline.java:250) 
at org.apache.cocoon.components.pipeline.CachingStreamPipeline.process(CachingStreamPipeline.java:395) 
at org.apache.cocoon.www.sitemap_xmap.resource_serialize_html(C:\programs\Tomcat-5.0\work\Catalina\localhost\epub\cocoon-files\org/apache/cocoon/www\sitemap_xmap.java:1119) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

in server.xml file I have configured as:

<parameter>
                    <name>url</name>
                    <value>jdbc:oracle:thin@epub_shirley:1521:minerva1</value>
               </parameter>
               <parameter>
                    <name>username</name>
                    <value>epub_app</value>
               </parameter>
               <parameter>

tnsname given as:

epub_shirley =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = jinx.dl.ac.uk)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SID = minerva1)
      (SERVER = DEDICATED)
    )
  )

why i am getting data source not found exception?