Hello,
I tested it under Firefox and it works fine. I have no doctype declaration in my *.ascx-File. Here is the "ValidatorCallout" part:
<%@ Control Language="C#" Inherits="YourCompany.Modules.lpBugreports.EditlpBugreports" CodeFile="EditlpBugreports.ascx.cs" AutoEventWireup="true" %>
<%@ Register TagPrefix="ajax" Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" %>v
<html>
<head></head>
<body>
<table align="left"> ...
<tr>
<td valign="top">
<asp:UpdatePanel ID="UpdatePanel5" runat="server">
<ContentTemplate>
<asp:TextBox ID="txbVersionsnummer" runat="server" CssClass="NormalTextbox"></asp:TextBox>
<asp:RequiredFieldValidator ID="reqVersionsnummer" runat="server" CssClass="NormalRed"
Display="None" resourcekey="reqVersionsnummer.ErrorMessage" ControlToValidate="txbVersionsnummer"></asp:RequiredFieldValidator>
<ajax:ValidatorCalloutExtender ID="ValidationExtender1" runat="server" TargetControlID="reqVersionsnummer"
Width="150" WarningIconImageUrl="~\images\warning.png" HighlightCssClass="validatorCalloutHighlight">
</ajax:ValidatorCalloutExtender>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr> ...
</table>
</body>
</html>Kevin