Custom sort is not working

Hi,

while i click on the header column. its not triggered custom sort function. If i have missed anything for below code.
function sort_custom(a, b, order) {
var n = a.length;
var m = b.length;
if (order == “asc”);
return n > m ? 1: -1;
else;
return n < m ? 1: -1;
}
mygrid = new dhtmlXGridObject(‘gridbox’);
mygrid.setImagePath("…/…/codebase/imgs/");
mygrid.setHeader(“Sales,Book Title,Author,Price,In Store,Shipping,Bestseller,Date of Publication”);
mygrid.setInitWidths(“50,150,100,80,80,80,80,200”);
mygrid.setColAlign(“right,left,left,right,center,left,center,center”);
mygrid.setColTypes(“dyn,ed,ed,price,ch,co,ra,ro”);
mygrid.setColSorting(“int,sort_custom,str,int,str,str,str,date”);
mygrid.setCustomSorting(sort_custom, 2);
mygrid.init();
mygrid.setSkin(“dhx_skyblue”);
mygrid.loadXML(“sample.xml”);

unfortunately the custom sorting is available in PRO version of the grid only.