Uncaught TypeError: Cannot read property 'aoColumns' of null

hello
i'm using jquery datatables plugin fixedColumns and i'm trying leave fixed three columns at left, i'm using a table that have a number of dynamic columns and this table filled with data of side of server in asp.net and when reload page appear a error like this..

"Uncaught TypeError: Cannot read property 'aoColumns' of null "

Can you help me please???


i left part of code below

function fnFixedColumnsDatatables() {
var oTable = $('.dataTable').dataTable({
"bJQueryUI": true,
"sScrollX": "100%",
"sScrollXInner": "150%",
"bScrollCollapse": true,
"oLanguage": { "sUrl": "Scripts/jquery.dataTables-ES.txt" },
"sPaginationType": "full_numbers",
"aoColumns": [ null ],
"sDom": '<"H"Tfrl>t<"F"ip>',
"oTableTools": {
"sRowSelect": "multi",
"sSwfPath": "Scripts/copy_csv_xls_pdf.swf",
"aButtons": [{ "sExtends": "copy", "bSelectedOnly": "true" }, "xls", "csv", "pdf"]
}
});
new FixedColumns(oTable, {
"iLeftColumns": 3,
"iLeftWidth": 350
});

<asp:GridView ID="gvReport" runat="server" AutoGenerateColumns="True" EnableViewState="False" CssClass="dataTable" >
<Columns>
<asp:TemplateField HeaderText="No.">
<ItemTemplate><%#Container.DataItemIndex + 1%></ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>