ValidatorEnable is not defined
<p>I am trying to enable and disable a required field validator using javascript but keep getting the error message ValidatorEnable is not defined. PLease find code below, any help would be great.</p>

<p><em>ASP.Net</em></p>

<pre><code>&lt;asp:RequiredFieldValidator EnableClientScript="True"  Display="None" ID="rfvMostRecentEmployer" ControlToValidate="txtMostRecentEmployer" runat="server" ErrorMessage="Most recent employer title is a required field"&gt;&lt;/asp:RequiredFieldValidator&gt;
</code></pre>

<p><em>Javascript</em></p>

<pre><code>var validatorMostRecentEmployer = document.getElementById('&lt;%= rfvMostRecentEmployer.ClientID %&gt;');

ValidatorEnable(validatorMostRecentEmployer, !hasCv);
</code></pre>

<p><em>Code Behind</em></p>

<pre><code>protected void Page_Load(object sender, EventArgs e)
{
    rblCV.Attributes.Add("onClick", string.Format("ShowCvOptions();"));
    ...
}
</code></pre>
