title: Required field validator is not working
body: <p>I have used a <em>required field validator</em>, on click of add Button error message will be displayed but whatever code written on onclick event will be executed even if the field is empty. </p>
  
  <pre><code>&lt;div class="form-group posrel"&gt;
      &lt;asp:Label ID="Label1" runat="server" AssociatedControlID="txtDept"&gt;&lt;i class="fa fa-pencil"&gt;&lt;/i&gt;&lt;/asp:Label&gt;
      &lt;asp:TextBox runat="server" ID="txtDept" placeholder="Department Name" ValidationGroup="ss1"&gt;&lt;/asp:TextBox&gt;
      &lt;div class="text-right validators"&gt;
          &lt;asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
              ErrorMessage="Department Name" ControlToValidate="txtDept" ValidationGroup="ss1"&gt;
          &lt;/asp:RequiredFieldValidator&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Below is the code snippet of add button - </p>
  
  <pre><code>&lt;div class="form-group pull-right"&gt;
      &lt;asp:LinkButton runat="server" ID="lnkbtnaddept" CssClass="btn btn-primary"  ValidationGroup="ss1" OnClick="lnkbtnaddept_Click"&gt;
          &lt;asp:Label runat="server" Text="Add" ID="lbladddept"&gt;&lt;/asp:Label&gt;
          &lt;i style="margin-left: 10px;" class="fa fa-send"&gt;&lt;/i&gt;
      &lt;/asp:LinkButton&gt;
  &lt;/div&gt;
  </code></pre>