Datatable Sorting Not Working.

I am using Jquery Datatable Plugin In my view page.Now i want to try to Sort My table column name i.e. roll no in ascending order...for that i used,

but i am getting the output in the form of: 1,10,11,2,22,3,4,5,6

I want:1,2,3,4,5,6,10,11,22

 

Thanks in advance