Validation Summary not appearing

I have to panels with custom validators and validation summaries but the employment one below is not showing when the amount box is invalid. But the treatment one for the numerical box works fine.

<!-- Employment History --> <asp:Panel ID="pnlEmployment" runat="server" DefaultButton="btnSaveEmployment"> <fieldset id="fieldsetEmployment" runat="server"> <legend>Employment History <span class="complete"> <label for="cbEmploymentHistoryComplete">Section Complete</label> <asp:CheckBox ID="cbEmploymentHistoryComplete" runat="server" CssClass="checkbox" TabIndex="15" /> <span style="position: absolute; top: -1px; right: 2px"> <span class="saving"> <img src="../images/ajax-loader.gif" alt="sa ...