Update Panel, Update Progress and DropDown List

Question

 <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
                  <Services>
            <asp:ServiceReference Path="Machine.asmx" />
         </asp:ScriptManager>
           <div align="center" style="width:auto" >
            <asp:UpdatePanel ID="up1" runat="server" Visible="true" UpdateMode="Conditional">
            <ContentTemplate> 
         <table class="nav-justified" border="1" id="table1">
             <tr>
                 <td>
                <asp:Label ID="Label2" runat="server" Text="Select Search Criteria"></asp:Label>
                 </td>
                 <td>
                     <asp:DropDownList ID="ddlSearchCriteria" runat="server" AutoPostBack="true" EnableViewState="true" OnSelectedIndexChanged="ddlSearchCriteria_SelectedIndexChanged" Height="30px" Width="200px">
                        <asp:ListItem Value="0">Select</asp:ListItem>
                         <asp:ListItem Value="1">All</asp:ListItem>
                          <asp:ListItem Value="2">Data Center</asp:ListItem>
                         </asp:DropDownList>
                 </td>
             </tr>
               <tr id="trDC" runat="server" visible="false"> <td>
                                    <asp:Label ID="lblRegion" runat="server" Text="Select DataCenter"></asp:Label>
                                </td>
                   <td>
                        <asp:DropDownList ID="ddlDC" runat="server" AutoPostBack="false" EnableViewState="true" OnSelectedIndexChanged="ddlDC_SelectedIndexChanged" Height="30px" Width="200px">
                                        <asp:ListItem Value="0">Select</asp:ListItem>
                                        <asp:ListItem Value="1">a </asp:ListItem>
                                    </asp:DropDownList></td>
               </tr>
           <tr id="tr1" runat="server" visible="false" >
               <td>
                   <asp:Label ID="lblOrder" runat="server" Text="Order For SOEID"></asp:Label>
               </td>
            <td >
                <asp:TextBox ID="txtOrderFor" runat="server" Height="20px" Width="200px"></asp:TextBox>
            </td>
               </tr>
             <tr>
                 <td>
                 </td>
                 <td>
                     <asp:Button ID="btnSearch" runat="server" Text="Search" OnClick="btnSearch_Click" />
                     <asp:Button ID="btnCancel" runat="server" Text="Cancel" OnClick="btnCancel_Click" />
                 </td>
             </tr>
         </table>
                 </div>
                 </ContentTemplate>
            </asp:UpdatePanel>
                    <asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="up1" DisplayAfter="0" DynamicLayout="false">
                        <ProgressTemplate>
                            <div style="position:absolute; left:45%;">
                                <div style="position:relative; left:45%;">
                                    <table border="0" align="center">
                                        <tr>
                                            <td>
                                             <img alt=""src="img/loading.gif" height="50px" width="50px" />
                                            </td>
                                        </tr>
                                    </table>
                                <center>
                                    Please wait...
                                </center>
                            </div>
                        </ProgressTemplate>
                    </asp:UpdateProgress>
                </div>
                
            
             <asp:UpdatePanel ID="up2" runat="server">
            <ContentTemplate> 
            <asp:Label ID="lblRows" runat="server" Font-Size="Large"  Visible="false" ></asp:Label>
                <asp:GridView ID="gvDetails" runat="server" AllowPaging="True" AutoGenerateColumns="False" CellPadding="3" CssClass="bootstrap dataTables_wrapper" DataKeyNames="Order_Item_Id”   EnableViewState="false" HeaderStyle-HorizontalAlign="Left" OnPageIndexChanging="gvDetails_PageIndexChanging" OnRowCommand="gvDetails_RowCommand" OnRowDataBound="gvDetails_RowDataBound" PageSize="15" ShowHeaderWhenEmpty="true" Visible="true" Width="100%">
                    <Columns>
                        <asp:TemplateField HeaderStyle-HorizontalAlign="Left" HeaderText="Select">
                      <ItemTemplate>
                          <asp:CheckBox ID="chkBox1" runat="server"  AutoPostBack="true" OnCheckedChanged="Check_Clicked"/>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:BoundField DataField="Order_Item_Id" HeaderStyle-HorizontalAlign="Left" HeaderText="Order Id" />
                         
                    </Columns>
                </asp:GridView>
                </div>
                <asp:Button ID="Button4" runat="server" Font-Bold="True" Font-Size="XX-Large" OnClick="Button4_Click" Text="Export To Excel" visible="false" />
                <asp:Button ID="Button3" runat="server" Font-Bold="True" Font-Size="XX-Large" OnClick="Button3_Click" Text="Submit"  Visible="false"   />
                <asp:Button ID="Button1" runat="server" Font-Bold="True" Font-Size="XX-Large" OnClick="Button1_Click" Text="Cancel" Visible="false" />
                </div>
           </ContentTemplate>
                  <Triggers> 
                            <asp:PostBackTrigger ControlID="Button4" /> 
                           <asp:PostBackTrigger ControlID="Button3" />
                       <asp:PostBackTrigger ControlID="Button1" />
                        </Triggers> 
                 </asp:UpdatePanel>

I have two update panel and 1 update progress on my aspx page. My first update panel contains two dropdown, on change of first dropdown, second populates and also there is a submit button in the update panel. When I use selectedindexchange of dropdown, Autopostback occurs, update progress works but I don't want it to work on that event. It should work only on the submit click. Second update panel contains the data to be shown on click of submit button. Also,My update progress is not in any of the update panel, it is in a div between both the update panel.