disable a column sorting using datatables of jquery

Question

hi, i am using datatables of jquery to sort the table fields.my question is how to disable particular column with out sorting . i tried with the following code ,but get excepted result.

"aoColumns": [
    { "bSearchable": false },
    null
]   

i also tried with following code

"aoColumnDefs": [
     { "bSearchable": false, "aTargets": [ 1 ] }
 ]

but the result is not accepted .please tell me any idea

usman