RadGrid Headers not displaying

[Bob]

I have the following code in my web page.  I want to use static headers and allow users to be able to scroll within a RadGrid.  Here is the code:

<table>
        <tr>
            <td>
                    <asp:gridview ID="gvSites"
                                  runat="server"
                                  AutoGenerateColumns="false"
                                  ShowHeader="true"
                                  HeaderStyle-HorizontalAlign="Left"
                                  ItemStyle-HorizonitalAlign="Left"
                                  ClientSettings-Scrolling-AllowScroll="true"
                                  ClientSettings-Scrolling-UseStaticHeaders="true"
                                  Height="575px">
                        <Columns>
                            <asp:TemplateField ItemStyle-Width="100px">
                                <ItemTemplate>
                                    <asp:Label ID="lblSiteCode" HeaderText="Site Code" runat="server" Text='<%# Eval("SiteCode")%>'></asp:Label>
                                </ItemTemplate>
                            </asp:TemplateField> 
                            <asp:TemplateField ItemStyle-Width="130px">
                                <ItemTemplate>
                                    <asp:Label ID="lblBranchNumber" HeaderText="Branch Number" runat="server" Text='<%# Eval("BranchNumber") %>'></asp:Label>
                                </ItemTemplate>
                            </asp:TemplateField> 
                            <asp:TemplateField ItemStyle-Width="150px">
                                <ItemTemplate>
                                    <asp:Label ID="lblLocationName" HeaderText="Location Name" runat="server" Text='<%# Eval("LocationName") %>'></asp:Label>
                                </ItemTemplate>
                            </asp:TemplateField>    
                    </Columns>                 
                </asp:gridview>
            </td>
        </tr>
</table>

But none of my header text is displaying.  What am I doing wrong?