How to toggle the second line of Bootstrap navbar

I am new to Bootstrap and I am building a navbar with a second row. The second line is only called when the search field it contains is required. To invoke it, I have an always-visible-style-link button that works fine in mobile widths, but won't hide it in desktop widths. What will I not get? Below is the HTML and here's a sample Bootply . Thanks in advance ... `

<div class="navbar-header">
  <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#nav1">
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
    <span class="icon-bar"></span>
  </button>
  <div class="btn-group">
        <a class="btn btn-inverse navbar-btn" href="#" title="Search" data-toggle="collapse" data-target="#nav2">
            <span class="glyphicon glyphicon-search white"></span>
        </a>    
        <a class="navbar-brand" rel="home" href="#" title="Title">Brand</a>         
    </div>
</div>


<div class="collapse navbar-collapse" id="nav1">
  <ul class="nav navbar-nav">
    <li class="active"><a href="#">Home</a></li>
    <li><a href="#about">About</a></li>
    <li><a href="#contact">Contact</a></li>
  </ul>
</div><!--/.nav-collapse -->


<div class="collapse navbar-collapse" id="nav2">
  <form class="navbar-form" role="search" id="srch-frm">
            <div class="input-group">
                <input class="form-control typeahead" placeholder="Search" name="pn" id="srch-term" type="text">
                <div class="input-group-btn">
                    <button class="btn btn-default" type="submit"><i class="glyphicon glyphicon-search"></i></button>
                </div>
            </div>
        </form> 
</div><!--/.nav-collapse -->

      

        
        
        
      

    

`