I dont enable a one div from another div

Question

 Here is my simple code:
<div id="time_enable" runat="server"><br />

  <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server"></asp:ToolkitScriptManager>

  <br />
  <asp:UpdatePanel ID="UpdatePanel1" runat="server">
  <ContentTemplate>
  <asp:Timer ID="Timer1" runat="server" Interval="1000" OnTick="Timer1_Tick" >
  </asp:Timer>
  <br />
  <br />
  <table style="position: absolute; top: 462px; left: 195px; width: 1010px; height: 124px;">
  <tr>
  <td><div class="circle"><asp:Label ID="Label13" runat="server"></asp:Label></div></td>
  <td style="text-align: left; font-family: 'Arial Black';"><b style="text-align: center; background-color: #FFFFFF;">DAYS</b></td>
  <td><div class="circle"><asp:Label ID="Label14" runat="server"></asp:Label></div></td>
  <td style="text-align: left; font-family: 'Arial Black';"><b style="text-align: center; background-color: #FFFFFF;"> HOURS</b></td>
  <td><div class="circle"><asp:Label ID="Label15" runat="server"></asp:Label></div></td>
  <td style="text-align: left; font-family: 'Arial Black';"><b style="text-align: center; background-color: #FFFFFF;"> MIN</b></td>
  <td><div class="circle"><asp:Label ID="Label16" runat="server"></asp:Label></div></td>
  <td style="text-align: left; font-family: 'Arial Black';"><b style="text-align: center; background-color: #FFFFFF;">  SEC</b></td>
  <td><b style="font-size: xx-large"><asp:Label ID="Label17" Text="=Remaining For Vote Day" runat="server" BackColor="White" Font-Bold="True" Font-Size="Medium" ForeColor="Blue"></asp:Label></b></td>
  </tr>
 
 
  </ContentTemplate>
  </asp:UpdatePanel>
  </div>
 <div id="theDiv1" runat="server" style="height: 182px">
  <table align="center" class="auto-style1" style="border-style: dashed; border-color: #008000; height: 179px; width: 366px; margin-left: 300px;">
  <tr>
  <td class="auto-style2">&nbsp;</td>
  <td>
  <asp:Label ID="Label1" runat="server" Font-Bold="true" Font-Size="X-Large" Text="Voter login"></asp:Label>
  </td>
  </tr>
  <tr>
  <td class="auto-style2">
  <asp:Label ID="Label2" runat="server" Text="Name"></asp:Label>
  </td>
  <td>
  <asp:TextBox ID="TextBox1" runat="server" Width="177px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td class="auto-style2">
  <asp:Label ID="Label3" runat="server" Text="Password"></asp:Label>
  </td>
  <td>
  <asp:TextBox ID="TextBox2" runat="server" TextMode="Password" Width="179px"></asp:TextBox>
  </td>
  </tr>
  <tr>
  <td class="auto-style2">&nbsp;</td>
  <td>
  <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Log in" Width="65px" />
  <asp:LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton1_Click">New User</asp:LinkButton>
  </td>
  </tr>
  <tr>
  <td class="auto-style2">&nbsp;</td>
  <td>
  <asp:LinkButton ID="LinkButton2" runat="server" OnClick="LinkButton2_Click">Forgot Password</asp:LinkButton>
  </td>
  </tr>
  </table>
  <asp:Label ID="label4" runat="server"></asp:Label>
  </div>
  In code behind:
  protected void Timer1_Tick(object sender, EventArgs e)
  {
 
  DateTime dt = DateTime.Now;
  TimeSpan differ;
  System.DateTime date1 = new System.DateTime(2015, 4, 1, 20, 10, 0);
  differ = date1.Subtract(dt);
  double t = differ.TotalSeconds;

  if (t > 0)
  {
  double dy, h, m, s;
  dy = differ.Days;
  h = differ.Hours;
  m = differ.Minutes;
  s = differ.Seconds;
  Label13.Text = dy.ToString();// +" Days " + h + " Hours " + m + " Minutes " + s + " Seconds left for celebration";
  Label14.Text = h.ToString();
  Label15.Text = m.ToString();
  Label16.Text = s.ToString();
  }
  else
  {
  Timer1.Enabled = false;
  time_enable.Visible = false;
  theDiv1.Visible = true;
  }
  }
 My question is that i visible thDiv1 div from Time1_tick(). But thDiv1 is not visible. How i will do?