submit button does not work with validators inside updatepanel - asp.net

Question

<asp:UpdatePanel runat="server" ID="UpdatePanel" UpdateMode="Always">
<ContentTemplate>
<asp:ListView ID="EditModeListView" runat="server" DataSourceID="DataSourceWrite">
<itemtemplate>
<tr class="cat" onclick="return ApplyTRToggle(this);">
<td colspan="5"><img src="/_layouts/images/COLLAPSE.GIF" class="toggle-img"/> <%# Eval("Cat.CategoryName")%></td>
</tr>
<asp:ListView ID="SubListView" runat="server" DataSource='<%# Eval("Blocks") %>' >
<ItemTemplate>
<tr class="sec" onclick="return ApplyTRToggle(this);">
<td></td>
<td><img src="/images/COLLAPSE.GIF" /><%# Eval("Block.CategoryName")%> </td>
<td></td>
<td><%# Eval("StringFormat") != null ? String.Format(Eval("StringFormat").ToString(), Eval("BlockSum")):Eval("BlockSum") %></td>
<td>
<asp:ListView ID="SuberListView" runat="server" DataSource='<%# Eval("Crits") %>' >
<ItemTemplate>
<tr>
<asp:HiddenField ID="Identifier" runat="server" Value='<%# DataBinder.Eval(Container.DataItem, "ValueID")%>' />
<td></td>
<td><%# Eval("Crit.CategoryName")%></td>
<td><%# Eval("CritUnit")%></td>
<td>
<asp:HiddenField runat="server" ID="IsDecimalController" Value='<%# DataBinder.Eval(Container.DataItem, "IsDecimal")%>' />
<asp:TextBox runat="server" ID="ValueControl" Text='<%# DataBinder.Eval(Container.DataItem, "CritSum")%>' MaxLength="12"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="ErrorMSG" ValidationGroup="NumbersValidation" ControlToValidate="ValueControl" Display="Dynamic"></asp:RequiredFieldValidator>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ValidationExpression='<%# Const.FLOAT_DIGITALS%>' ValidationGroup="NumbersValidation" ErrorMessage="ErrorMSGG" ControlToValidate="ValueControl" Display="Dynamic" />
</td>
<td><%# DataBinder.Eval(Container.DataItem ,"Crit.Comment")%></td>
</tr>
</ItemTemplate>
<LayoutTemplate>
<div ID="itemPlaceholder" runat="server"></div>
</LayoutTemplate>
</asp:ListView>
</td>
</tr>
</ItemTemplate>
<LayoutTemplate>
<tr ID="itemPlaceholder" runat="server"></tr>
</LayoutTemplate>
</asp:ListView>
</itemtemplate>
<layouttemplate>
<table border="0" cellpadding="0" cellspacing="0" width="100%">
<div runat="server" ID="itemPlaceholder">
</div>
</table>
<div class="indicators-toolbar">
<asp:Button runat="server" ID="saveButton" Text="Save" ValidationGroup="NumbersValidation" CausesValidation="true" onclick="saveButton_Click"/>
<asp:Button runat="server" ID="cancelButton" Text="Cancel" CssClass="ms-ButtonHeightWidth" CausesValidation="false" onclick="cancelButton_Click"/>
</div>
</layouttemplate>
</asp:ListView>
</ContentTemplate>
</asp:UpdatePanel>
that's in my usercontrol. the problem is when type no valid text or leave empty in <asp:TextBox runat="server" ID="ValueControl" Text='<%# DataBinder.Eval(Container.DataItem, "CritSum")%>' MaxLength="12"></asp:TextBox> fires requiredfield validator and shows error text.. then press submit button, nothing happens, but then after typing correct text in textboxes and no validator fires submit button does NOT work. How to solve the problem

Answer 1

while click on button fire a trigger in ajax.....
it may help to you
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="imgbtnSubmit" EventName="Click" />
</Triggers>
</asp:UpdatePanel>