The problem is that the [`asp:login`][asp:login] control modifies the id's of it's children, so the [`asp:panel`][asp:panel] control does not know where to look to find the new `DefaultButton` id.

### Here's a simplified version that reproduces the issue:



<pre><code>&lt;asp:Panel ID=&quot;AZloginPanel&quot; runat=&quot;server&quot; <b>DefaultButton=&quot;LoginButton&quot;</b>&gt;
    &lt;asp:Login ID=&quot;LoginUser&quot; runat=&quot;server&quot; &gt;
        &lt;LayoutTemplate&gt;
            &lt;asp:TextBox ID=&quot;UserName&quot; runat=&quot;server&quot; /&gt;
            &lt;asp:TextBox ID=&quot;Password&quot; runat=&quot;server&quot; TextMode=&quot;Password&quot; /&gt;
            &lt;asp:Button ID=&quot;LoginButton&quot; runat=&quot;server&quot; Text=&quot;Log In&quot; /&gt;
        &lt;/LayoutTemplate&gt;
    &lt;/asp:Login&gt;
&lt;/asp:Panel&gt;
</code></pre>

If you want to use a [DefaultButton for a LoginControl][Default Login], you can do one of two things:

### 1. Nest the panel inside of the login control:

<pre><code>&lt;asp:Login ID=&quot;LoginUser&quot; runat=&quot;server&quot; &gt;
    &lt;LayoutTemplate&gt;
        <b>&lt;asp:Panel runat=&quot;server&quot; DefaultButton=&quot;LoginButton&quot;&gt;</b>
            &lt;asp:TextBox ID=&quot;UserName&quot; runat=&quot;server&quot; /&gt;
            &lt;asp:TextBox ID=&quot;Password&quot; runat=&quot;server&quot; TextMode=&quot;Password&quot; /&gt;
            &lt;asp:Button ID=&quot;LoginButton&quot; runat=&quot;server&quot; Text=&quot;Log In&quot; /&gt;
        <b>&lt;/asp:Panel&gt;</b>
    &lt;/LayoutTemplate&gt;
&lt;/asp:Login&gt;
</code></pre>

### 2. Build the ID with the LoginControlID then `$` then Button ID:

<pre><code>&lt;asp:Panel ID=&quot;AZloginPnl&quot; runat=&quot;server&quot; <b>DefaultButton=&quot;LoginUser$LoginButton&quot;</b>&gt;
    &lt;asp:Login ID=&quot;<b>LoginUser</b>&quot; runat=&quot;server&quot; &gt;
        &lt;LayoutTemplate&gt;
            &lt;asp:TextBox ID=&quot;UserName&quot; runat=&quot;server&quot; /&gt;
            &lt;asp:TextBox ID=&quot;Password&quot; runat=&quot;server&quot; TextMode=&quot;Password&quot; /&gt;
            &lt;asp:Button ID=&quot;<b>LoginButton</b>&quot; runat=&quot;server&quot; Text=&quot;Log In&quot; /&gt;
        &lt;/LayoutTemplate&gt;
    &lt;/asp:Login&gt;
&lt;/asp:Panel&gt;
</code></pre>

[asp:login]: http://msdn.microsoft.com/en-us/library/vstudio/ms178329(v=vs.100).aspx
[asp:panel]: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.panel(v=vs.110).aspx
[Default Login]: http://weblogs.asp.net/jongalloway/asp-net-setting-the-defaultbutton-for-a-login-control

I am developing a website on ASP.NET and using bootstrap for the design. I'm using modal fade class (like a popup) for user to login.

Here's my code:
        
    <div class="modal fade" id="login" role="dialog">
       <asp:Panel ID="AZloginPanel" runat="server">
          <div class="modal-dialog">
             <div class="modal-content">
                <div class="form-horizontal">
                   <div class="modal-header">
                      <h4>Login</h4>
                   </div>
                <div class="modal-body">
                   <asp:Login ID="LoginUser" runat="server" EnableViewState="false" RenderOuterTable="false">
                      <LayoutTemplate>
                         <span class="failureNotification">
                            <asp:Literal ID="FailureText" runat="server"></asp:Literal>
                         </span>
                         <asp:ValidationSummary ID="LoginUserValidationSummary" runat="server" CssClass="failureNotification"
                                            ValidationGroup="LoginUserValidationGroup" />
                         <div class="accountInfo">
                            <fieldset class="login">
                               <div class="form-group">
                                  <asp:Label ID="UserNameLabel" CssClass="col-lg-2 control-label" runat="server" AssociatedControlID="UserName">Username:</asp:Label>
                                    <div class="col-lg-10">
                                       <asp:TextBox ID="UserName" runat="server" CssClass="form-control" placeholder="Username"></asp:TextBox>
                                    </div>
                                    <asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="UserName"
                                                        CssClass="failureNotification" ErrorMessage="User Name is required." ToolTip="User Name is required."
                                                        ValidationGroup="LoginUserValidationGroup">*</asp:RequiredFieldValidator>
                               </div>
                               <div class="form-group">
                                  <asp:Label ID="PasswordLabel" CssClass="col-lg-2 control-label" runat="server" AssociatedControlID="Password">Password:</asp:Label>
                                  <div class="col-lg-10">
                                     <asp:TextBox ID="Password" runat="server" CssClass="form-control" placeholder="Password" TextMode="Password"></asp:TextBox>
                                  </div>
                                  <asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="Password"
                                                        CssClass="failureNotification" ErrorMessage="Password is required." ToolTip="Password is required."
                                                        ValidationGroup="LoginUserValidationGroup">*</asp:RequiredFieldValidator>
                               </div>
                               <p>
                                  <asp:CheckBox ID="RememberMe" runat="server" />
                                  <asp:Label ID="RememberMeLabel" runat="server" AssociatedControlID="RememberMe" CssClass="inline">Keep me logged in</asp:Label>
                               </p>
                            </fieldset>
                            <div class="modal-footer">
                               <p class="pull-left">
                                    <asp:HyperLink ID="RegisterHyperLink" runat="server" EnableViewState="false" NavigateUrl="~/Account/Register.aspx">Register</asp:HyperLink>if you don't have an account.
                               </p>
                                  <asp:Button ID="CloseModal" runat="server" CssClass="btn btn-info" CommandName="Close" Text="Close" />
                                  <asp:Button ID="LoginButton" runat="server" CssClass="btn btn-primary" CommandName="Login" Text="Log In" ValidationGroup="LoginUserValidationGroup" />
                             </div>
                         </div>
                      </LayoutTemplate>
                   </asp:Login>
                </div>
             </div>
          </div>
       </div>
    </asp:Panel>
    </div>

When I set `DefaultButton="LoginButton"` in `AZloginPanel` panel, I get the following error:

> The DefaultButton of 'AZloginPanel' must be the ID of a control of type IButtonControl.

I'm lost and I've tried everything but it seems I'm at dead end.

Any ideas?