Why does the button in a user control have to be clicked twice to trigger the click event??

I have a simple user control and there is a button in that user control:
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="WebUserControl1.ascx.cs"     Inherits="WebApplication1.WebUserControl1" %>
<div>     <asp:Button ID="Button1" runat="server" Text="Button" OnClick="buttonclick" /> </div>
I put this user control on a webpage. This webpage also has a timer, and when the timer ticks, the page will reload the user control. My problem is that the button in that user control has to be clicked twice to trigger the button click event. If I set timer interval to a long period, it will work properly. But in my case, I want to set the interval to 1 second. Can anyone help me solve this issue please?
Below is the code for that webpage: <form id="for ...