after giving RequiredFieldValidator the logout button not working

<pre>
    <tr>
    <td align="left">&nbsp;
    <asp:label id="lblOpenid" cssclass="lblOpen" runat="server" text="Open jobs By Specific Id" xmlns:asp="#unknown">
    </asp:label>
    <asp:textbox id="TextBox1" runat="server" width="78px" causesvalidation="true" xmlns:asp="#unknown">
    </asp:textbox>
    <asp:button id="Button1" runat="server" text="Click" onclick="Button1_Click" xmlns:asp="#unknown" /><br />
    <asp:requiredfieldvalidator id="RequiredFieldValidator1" runat="server" controltovalidate="TextBox1" errormessage="Plz enter Problem ID"        xmlns:asp="#unknown">
    </asp:requiredfieldvalidator>
        </td>
    </tr>
    <tr>
    <td align="left">&nbsp
    <asp:label id="lblCloseid" cssclass="lblClose" runat="server" text="Close jobs By Specific Id" xmlns:asp="#unknown">
    </asp:label>
    <asp:textbox id="TextBox2" runat="server" width="76px" causesvalidation="true" xmlns:asp="#unknown">
    </asp:textbox>
    <asp:button id="Button2" runat="server" text="Click" onclick="Button2_Click" xmlns:asp="#unknown" />
    <br />
    <asp:requiredfieldvalidator id="RequiredFieldValidator2" runat="server" controltovalidate="TextBox2" errormessage="Plz enter Problem ID"            xmlns:asp="#unknown">
    </asp:requiredfieldvalidator>
    </td>
    </tr>
   <table>
   <tr>
   <td style="width: 211px" valign="top" align="center">
   <asp:button id="btnLogout" runat="server" backcolor="#6699cc" bordercolor="#6699cc" xmlns:asp="#unknown"
                        BorderStyle="None" CausesValidation="true" ForeColor="White" OnClick="btnLogout_Click"
                        Text="Logout" Visible="true" Width="98px" />
   </asp:button>
   </td>

   </tr>
   </table>
</pre>