Server side validation for required fields
<p>I am having an issue with the requiredfieldvalidator control not working on an ASP.net page.  I have completed the attributes of that field properly, but when I test it, the postback is allowed to happen even if the field in question is blank.  </p>

<p>So I want to do server side validation instead.  What is the best way to do that?  In the event that caused the postback?  Also, if I find out the field is blank, how do I get the user back to the screen with all other values they placed on other fields intact and a message saying "This field cannot be blank".</p>

<p>EDIT:</p>

<p>This is the code:</p>

<pre><code>&lt;asp:TextBox ID="fName" TabIndex="1" runat="server" Width="221px" CausesValidation="True"&gt;&lt;/asp:TextBox&gt;
&lt;asp:RequiredFieldValidator ID="FNameRequiredFieldValidator" runat="server"
        ControlToValidate="fName" InitialValue="" ErrorMessage="Filter Name cannot be blank."
        ToolTip="Filter Name cannot be blank."&gt;*&lt;/asp:RequiredFieldValidator&gt;
</code></pre>
