I've added this to both Joomla 2.5 and 1.5 sites. The 2.5 site works fine, but the 1.5 site get this error after the search:

Fatal error: Call to undefined method K2HelperUtilities::getParams() in /home/signonhg/public_html/reunionplanner/plugins/system/K2Filter/views/itemlist/view.html.php on line 20

What should I do to resolve this?

Thanks,
Neal