Not able to log data in Search keyword with no results

I want to log data in search keyword with no results field of site Search.
Below is my code

var searchKey = false;
searchKey = true;
_paq.push([‘trackSiteSearch’,$(’#backHaulEstCost’).val().trim(),‘Back Haul Est Cost’]);
//_paq.push([ ‘trackSiteSearch’, keywords + ‘’, 0 ]);
var searchCount = 0; // set this value when rendering the search result page
_paq.push([‘setCustomUrl’, document.URL + ‘&search_count=’ + searchCount]);
Please tell me how i can log data into Search Keywords with no Result widget