DataTable fnFilter not working on single column

orizis

I am trying to use fnFilter, and if I pass only the first argument(string to filter) it works fine. If I am adding the second param (column to filter) it's not filtering anymore.

My code (when it's working on all columns):

function onClick(e, dt, button, config) {
    $('.datatable').dataTable().fnFilter('text');
 }

My code when it's not working:

function onClick(e, dt, button, config) {
    $('.datatable').dataTable().fnFilter('text', 2, false, false);
 }

Any thoughts?
Thanks :)