can't get fnFilter to work

aurora

I'm trying to filter a column using a seperate textbox, working on this code for near 10 hours but I couldn't find what is wrong about it. "q" is id of a textbox. Even the alert function doesn't work:
[code]
var oTable;
$(document).ready(function () {
oTable = $('#ContentPlaceHolder1_GridView1').dataTable({
"bFilter": true,
"bPaginate": false,
"bLengthChange": false,
"bAutoWidth": false,
"bSort": false,
"bInfo": false,
});
$("#q").keyup(function () {
alert("key pressed");
oTable.fnFilter("d");
});
});
[/code]