Errors While installing solr plugin

I am trying to get solr-plugin to work with omeka
and jetty I am running into the following error

PHP Warning: require_once(HELPER_DIR/UrlFunctions.php): failed to open stream: No such file or directory in /var/www/html/omeka/plugins/SolrSearch/helpers/SolrSearch_IndexHelpers.php on line 4
[Mon Aug 05 15:50:57 2013] [error] [client] PHP Fatal error: require_once(): Failed opening required 'HELPER_DIR/UrlFunctions.php' (include_path='/var/www/html/omeka/application/libraries:/var/www/html/omeka/application/models:.:/usr/share/pear:/usr/share/php:/var/www/html/omeka/plugins/SolrSearch/models') in /var/www/html/omeka/plugins/SolrSearch/helpers/SolrSearch_IndexHelpers.php on line 4

Is there anyone out there who has come accross this one and if so could you help me get past it.

thanks in advance

My first guess is that you are running Omeka 2.0, but that the Solr plugin hasn't been updated for it yet. Does that sound like a possibility?

That is it. Thank you for the answer