Table loading Ajax data twice

I love dataTables - thank you very much.

I have a dataTables table that loads via ajax. It load the data twice. How can I stop this please?

		// set up tables
		var contactTable = $("#contactTable").dataTable( {
    	    "sScrollY": "200px",																					// the value set here is irrelevant as it's set by pageResizing()
			"bProcessing": true,
			"sPaginationType": "full_numbers",
			"iDisplayLength": 25,
    		"aLengthMenu": [[10, 20, 25, 40, 50, 100, 250, 500<% if cint(contactCount) < 5000 then response.write ", -1" %>], [10, 20, 25, 40, 50, 100, 250, 500<% if cint(contactCount) < 5000 then response.write ", 'All'" %>]],
			"bLengthChange": true,
			"bServerSide": true,
			"sAjaxSource": "SSP_EmailEvents.asp?CampaignID=<%=campaignID%>&eventType=<%=eventType%>",
			"aoColumnDefs": [
			    { "aDataSort": [ 4 ], "aTargets": [ 2 ] },
				{ "bVisible": false, "aTargets": [ 4 ] }									
			],
			"aaSorting": [[ 2, "asc" ]],
			"sDom": 'T<"clear">lfrtip',
			"oTableTools": {
				"aButtons": [ "copy", "csv" ]
			}
		} ); 

Thanks.