Error on search filter

Hi,

I have a search which filter by a custom list field & it gives an error
"An nlobjSearchFilter contains an invalid operator, or is not in proper syntax: custbody_select_job_for_costing. "

Also tried using the search operator "is" ,but no use

Am I doing something wrong here?
Any help is appreciated.

function SOTotalCalc()  {   //to calulate the total amount for the Salesorder   var sumSOColumns = new Array();   sumSOColumns[0] = new nlobjSearchColumn('amount', null, 'sum');//custbody_select_wo_for_costing   var sumSOFilters = new Array();   sumSOFilters[0] = new nlobjSearchFilter('mainline',null,'is','T',null);    sumSOFilters[1] = new nlobjSearchFilter('custbody_select_job_for_costing', null, 'anyof', jobID, null);   var sumSOResults = nlapiSearchRecord('salesorder', null, sumSOFilters, sumSOColumns);   var sumSOResult = sumSOResults[0];   sumSO = sumSOResult.getValue('amount', null, 'sum');   emailmsg += "sumSO :"+sumSO+"n";  }