DT column search value not sent to server

HTML

<script src="http://code.jquery.com/jquery-2.1.3.min.js"></script>
<script src="http://cdn.datatables.net/1.10.7/js/jquery.dataTables.min.js"></script>
<script src="http://cdn.datatables.net/plug-ins/1.10.7/integration/bootstrap/3/dataTables.bootstrap.min.js"></script>
<table id="dataTable" class="table table-bordered table-condensed table-striped">
	<tfoot>
		<tr>
			<th>EmpNum</th>
		</tr>
	</tfoot>
  <thead>
		<tr>
		  <th>EmpNum</th>
		</tr> 
	</thead>
	
</table>

JavaScript

$(document).ready(function () {
			var table = $("#dataTable").DataTable({
				columnDefs: [
					{
						targets: 0,
						className: "searchable",
						name: "EmpNum",
						type: "string",
						data: "EmpNum",
						orderable: true,
						searchable: true
					}
				],

				lengthMenu: [10, 25, 50, 75, 100 ],
				autoWidth: false,
				order: [[0, "asc"]],
				searching: false,
				serverSide: true,
				//stateSave: true,
				//stateDuration: -1,		// Store in session
				pagingType: "full_numbers",
				ajax: {
					url: "/echo/json/",
					type: "POST"
				}
			});

			// Setup - add a text input to footer cell of searchable columns
			// Sources: https://datatables.net/examples/api/multi_filter.html
			//          https://datatables.net/reference/api/columns().footer()
			//          https://datatables.net/forums/discussion/23962/individual-columns-search-based-on-the-searchable-value-of-the-col
			table.columns(".searchable").every(function(){
				var title = $('#dataTable thead th').eq( this.index() ).text();
				$( this.footer() ).html( '<input type="text" placeholder="Search '+title+'" />' );

				var col = this;
				var timer;
				var frequency = 1000;

				$( 'input', this.footer() ).on( 'keypress change', function (evt) {
					var input = this;

					clearTimeout(timer);
					timer = setTimeout(function(){
						var searchVal = input.value;
                        alert("Searching for: " + searchVal);
						col.search("fooBar").draw();
					}, frequency);
				} );
			});

		});