full body background image with twitter bootstrap

I am trying to implement full body background image with twitter bootstrap but it is not working i am checking in full screen mode it is working in the mobile and tablet mode.

this is the html

    <div id="header">

  <nav class="navbar navbar-inverse navbar-fixed-top">
      <div class="container">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">Hifzil</a>
        </div>
        <div id="navbar" class="collapse navbar-collapse">
          <ul class="nav navbar-nav">
            <li class="active"><a href="#">Home</a></li>
            <li><a href="#about">Spelling Test</a></li>
            <li><a href="#contact">Practise Writing</a></li>
           <li><a href="#about">Spelling Game</a></li>
            <li><a href="#contact">English Dictionary</a></li>
               <li><a href="#about">Games</a></li>
            <li><a href="#contact">Support</a></li>

         </ul>
              <ul class="nav navbar-nav navbar-right">
      <li><a href="#"><span class="glyphicon glyphicon-user"></span> Sign Up</a></li>
      <li><a href="#"><span class="glyphicon glyphicon-log-in"></span> Login</a></li>
    </ul>
        </div><!--/.nav-collapse -->
      </div>
    </nav>

        <div id="boundry">
        <div class="searchbutton">  <a href="dic.php">Click Here To Start E-learning Drive !</a></div>      

            </div>
            </div>


<div class="col-md-9 text-center col-centered">
<div class="grade-module intro1">  <a href="#" class="gradeStyle blue1-bg">English</a> <div class="bd-grade blue1-bdr">
            <p class="text">Counting objects, fewer and more, names of colors, inside and outside, longer and shorter, and more.</p>
        </div>
        </div>
        <div class="grade-module intro2">
          <a href="dic.php" class="gradeStyle orange1-bg">Dictionary</a> <div class="bd-grade orange-bdr"><p class="text">Learn New Words From Dictionary And Their Meanings,Parts Of Speeches And Their Visualization</p></div>
         </div>
         <div class="grade-module intro3">
          <a href="paint.php" class="gradeStyle green-bg">Speeling Practice</a> <div class="bd-grade green-bdr"><p class="text">Practice Speelings By Drawing The Words . All you have to paint inside the letter not outside</p></div>
         </div>
         <div class="grade-module intro4">
          <a href="#" class="gradeStyle red-bg">Quiz</a> <div class="bd-grade red-bdr"><p class="text">Speeling quiz can provide you the opportunity to revise whether you have correctly memorize or not </p></div>
         </div>
         <div class="grade-module intro5">
          <a href="#" class="gradeStyle light-bg">Games</a> <div class="bd-grade light-bdr"><p class="text">Learning by increasing vocubulary from playing games like words search , scrabble and letterrace .</p></div>
         </div>
           <div class="grade-module intro6">
          <a href="#" class="gradeStyle voilet-bg">Visualization</a> <div class="bd-grade voilet-bdr"><p class="text">Visualization of words tends to lead towards learning and memorizing the words , their description and meaning</p></div>
         </div>
</div>

this is the css

#header{
    background: url('..images/english.jpg') no-repeat center top;
    padding-top: 200px;
    text-align: center;
    background-attachment: relative;
    background-position: center center;
    min-height: 670px;
    width: 100%;
    -webkit-background-size: 100%;
    -moz-background-size: 100%;
    -o-background-size: 100%;
    background-size: 100%;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;

}