在CustomValidator中使用图片作为ErrorMessage

<asp:CustomValidator ID="CustomvalidatorTCs" runat="server" Font-Bold="True"               Display="Dynamic" OnServerValidate="IAgreeCheck"  EnableClientScript="true" Text="<img src='../Common/Images/left_arrow.gif' />" ClientValidationFunction="iAgreeCheck"                                        ValidationGroup="OEGroup"></asp:CustomValidator>