Why a filter error on search

This script was working correctly for as long as I can remember. Can anyone determine why I would be getting a "nlobjSearchFilter contains an invalid operator"? I am searching on 'transaction' records

 // customerId is parameter passed in  var orderTypes = new Array(1,2);  var x = 0;  try {  // Find all transactions with this customer's ID associated with them  filters[x++] = new nlobjSearchFilter("name", null, 'anyof', customerId, null);  // Custom list  filters[x++] = new nlobjSearchFilter("custbody_partner_ordertype", null, 'anyof', orderTypes, null);  // type is Sales Orders  filters[x++] = new nlobjSearchFilter("type", null, 'anyof', "SalesOrd", null);  // status isnot "Cancelled"  filters[x++] = new nlobjSearchFilter("status", null, 'noneof', "Cancelled", null);  // mainline is true "T" - grab only summary transaction  filters[x++] = new nlobjSearchFilter("mainline", null, 'is', "T", null);  } catch (e) {}