Export to excel not working with colspan

The code I use for exporting my grid to excel is as follows :

var mygrid2;
function doInitGrid(){
mygrid2 = new dhtmlXGridObject(‘mygrid_container2’);
mygrid2.setHeader(“Excel ID,Uploaded Date”);

mygrid2.loadXML(" …");
window.onload =doInitGrid;

However when I add headers in this format , export doesnt work :-
mygrid2.setHeader(“Report Information,#cspan”);
mygrid2.attachHeader(“Excel ID,Uploaded Date”);

Can you pls tell me how I can make it work with colspans !

Pls note that I am not using
because I dont want data to be sent to an external server.

there is export tools for grid for php, java and .net backend, which one are you using?