asp.net - gridview dynamic hyperlink item templates

Hello Experts,
c#, asp.net, dynamic data web application:

I have a gridview that displays a hyperlink for the FILENAME column.  The text displayed to the user is "VIEW FILE".  When the user clicks on it a new browser is displayed with the contents of that file.  Here is the gridview code:

            <asp:GridView ID="GridView1" runat="server" DataSourceID="GridDataSource" EnablePersistedSelection="true"
                AllowPaging="True" AllowSorting="True" CssClass="DDGridView"
                RowStyle-CssClass="td" HeaderStyle-CssClass="th" CellPadding="6"
                AutoGenerateColumns="false">
                <Columns>
                    <asp:DynamicField DataField="SCENARIO" />
                    <asp:DynamicField DataField="SERVER" />
                    <asp:DynamicField DataField="RESULT" />
                    <asp:TemplateField HeaderText="FILENAME">
                    <ItemTemplate>
                    <asp:HyperLink runat="server" ID="FILENAME" NavigateUrl='<%# Eval("FILENAME") %>' Target="_blank"  >VIEW FILE</asp:HyperLink> 
                    </ItemTemplate>
                    </asp:TemplateField>                    
                    <asp:TemplateField>
                        <ItemTemplate>                        
                            <asp:DynamicHyperLink runat="server" Action="Edit" Text="Edit"
                            />&nbsp;<asp:LinkButton runat="server" CommandName="Delete" Text="Delete"
                                OnClientClick='return confirm("Are you sure you want to delete this item?");'
                            />&nbsp;<asp:DynamicHyperLink runat="server" Text="Details" />
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>            

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What I would like to do is not display the text "VIEW FILE" if that column does not have a file (empty string or null).  Any ideas?