Probleme with two update panel in same page

<asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
            <asp:Timer runat="server" ID="UpdateTimer" Interval="3000"    OnTick="UpdateTimer_Tick" />
            <h2>
                <asp:Label runat="server" Font-Size="Small" Font-Names="verdana" ID="lblmsg" />
            </h2>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="UpdateTimer" EventName="Tick" />
        </Triggers>
    </asp:UpdatePanel>

 <asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
<asp:DropDownList ID="_ddlDist" ClientIDMode="Static" runat="server" Style="background-color: #DEDFDE;"
                        AutoPostBack="true" CssClass="ddl" OnSelectedIndexChanged="_ddlDist_SelectedIndexChanged" CausesValidation="True"
                        data-rel="chosen" required >
                    </asp:DropDownList>
 </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="_ddlDist" EventName="SelectedIndexChanged" />
        </Triggers>
    </asp:UpdatePanel>