Fck editor required validation in asp.net C# for Google chro

Question

<script type="text/javascript">

    function ValidateContentText(source, args) {

        var fckBody1 = FCKeditorAPI.GetInstance('<%=txtproduct_detail.ClientID%>');

        args.IsValid = fckBody1.GetXHTML(true) != "";

    }

    </script>

 <FCKeditorV2:FCKeditor ID="txtproduct_detail" runat="server" Height="300">

                                            </FCKeditorV2:FCKeditor>

                                             <asp:CustomValidator runat="server" ID="CustomValidator2" ControlToValidate="txtproduct_detail"

                                                SetFocusOnError="true" Display="dynamic" ErrorMessage="*" ClientValidationFunction="ValidateContentText"

                                                ValidateEmptyText="true"></asp:CustomValidator>

i used this code, it work in Firefox but not in google Chrome

please help me