Fixing grid header

Fixing grid header

I am a starter on jquery, I want to fix the grid header on my website. I follow the information in http://plugins.jquery.com/plugin-tags/fixed-header.

I add the following codes into my module (.ascx file)
---------------------------------------------------------------------
<Style type="text/css">
.gv, .gvtest
{
    border: 1px solid #E2E2E2;
    border-collapse: collapse;
    padding: 2px;
}
.gvh
{
    background-color: #EEEEEE;
    font-weight: bold;
    color: #666666;
    font-size: 12px;
    text-align: center;
}
.gvr
{
    background-color: #FFFFFF;
}
.gva
{
    background-color: #EFEFEF;
}

</Style>
<script src="jquery.fixedtableheader.min.js" type="text/javascript"> </script>

<script type="text/javascript">
    $(function() {
        $(".gv").fixedtableheader({ highlightrow: true, highlightclass: "highlight" });
        $("#gridReports").fixedtableheader();
       
    });


</script>

    <asp:GridView ID="gridReports" CssClass="gv" runat="server"
        EnableTheming="False"
        GridLines="None"
        BorderStyle="None"
        CellPadding="2"
        ShowFooter="True"
        FooterStyle-CssClass="gridReports-RowBorder gridReports-font-bold"
        FooterStyle-BackColor="Cyan"
        FooterStyle-HorizontalAlign="Center">
        <HeaderStyle CssClass="gvh" />
        <RowStyle CssClass="gvr" />
        <AlternatingRowStyle CssClass="gva" />
    </asp:GridView>
--------------------------------------------------------------------------------
It can hold the grid header in firefox 3.5.2, but when I test in IE8, it come out a java error, and the header to the grid fix on the bottom part of the webpage. The error line is

<script type="text/javascript" > $('div.mojo-accordion').accordion(); $('div.mojo-accordion-nh').accordion({autoHeight: false}); $('div.mojo-tabs').tabs(); </script>

What is the cause of the error? And how can I solve it? Thanks a lot if anyone have any idea.