Sorting numbers in Extended Grid

When I try to sort numbers in a Extended Grid, it uses alphabetical algorithm.
Ex:
Extended Grid Sort: 1 - 108 - 11 - 2 - 25 ....
Right Order: 1 - 2 -11 - 25 - 108 ...

Does anybody can help me?
Thanks!

I've found the solution:

var money = new AW.Formats.Number;
money.setTextFormat("#,###.##");
obj.setCellFormat(number, 1);

Thanks!