After completing the Try it Out: 'Extending the Contact Form', the browser displays the asterisks correctly given the particular user input, but omits the error message. I checked the markup for ContactForm.ascx with the supplied code I downloaded from the Wrox website, and it matches correctly.
Here is the markup of one of the validation controls, which is similar to the other controls in the exercise in that they all have Display set to Dynamic, and an Error Message.
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server"
ErrorMessage="PLease enter an e-mail address."
Again, the page works correctly in the browser except that the Error Messages are not displayed. Thanks.