TextBoxWatermarkExtender for password textbox

Hi 
i have include TextBoxWatermarkExtender for my password textbox but when i run it, it show points as its mode is password. so any solution to show the watermark text??!!

<div class="form-group"> <asp:TextBox ID="txtUserName" runat="server" ></asp:TextBox> <asp:Label ID="wronglogusernamelbl" runat="server" ForeColor="#CC0000"></asp:Label> <asp:TextBoxWatermarkExtender ID="usernamebxwatermark" runat="server" TargetControlID="txtUserName" WatermarkCssClass="watertext" WatermarkText="Your User Name" Enabled="True"></asp:TextBoxWatermarkEx ...