Thread:Extension talk:SphinxSearch/incategory parameter return fatal error

When I type to search incategory:word then it returns server blank page with php fatal error: Fatal error: Call to a member function selectField on a non-object in E:\usr\Apache2.2\htdocs\wiki\extensions\SphinxSearch\SphinxMWSearch.php on line 298

SphinxMWSearch.php, line 298: it's within function filterByCategory:

My configuration: