Не выбирается первый чекбокс. Почему?

function inver_checkbox(name_form_inv) { 
 
  var obj_form_checked = document.forms[name_form_inv]; //.form_checkbox_object; 
 
  for (i = 0; i < obj_form_checked.elements.length; i++) { 
    if (obj_form_checked.elements[i].type == 'checkbox') { 
      if (obj_form_checked.elements[i].checked) { 
        obj_form_checked.elements[i].checked = false; 
      } else 
        obj_form_checked.elements[i].checked = true; 
    } 
 
  } 
 
 
  return (false); 
}

.dialog-msg { 
  max-height: 400px; 
  overflow: auto; 
} 
 
.FS18 { 
  font-size: 18px; 
} 
 
.user-contact a.btn { 
  color: #fff; 
} 
 
.panel-msg-btn { 
  margin: 0 0 10px 0; 
  background-color: #f0f5f9; 
} 
 
.table-filter-msg { 
  background-color: #fff; 
  border-bottom: 1px solid #e3eef5; 
} 
 
.table-filter-msg tbody tr:hover { 
  cursor: pointer; 
  background-color: #f0f5f9; 
} 
 
.table-filter-msg tbody tr td { 
  border-top-color: #e3eef5; 
} 
 
.table-filter-msg tbody tr.selected td { 
  background-color: #e3eef5; 
} 
 
.table-filter-msg .media-photo { 
  -webkit-border-radius: 50% !important; 
  -moz-border-radius: 50% !important; 
  border-radius: 50% !important; 
} 
 
.table-filter-msg .media .title {} 
 
.table-filter-msg .media a { 
  color: inherit; 
}

  <link href="http://koty-online.ru/templates/adaptive/boostrap/css/bootstrap.min.css" rel="stylesheet" /> 
  <form method="post" name="del_dialogs"> 
    <table class="table panel-msg-btn text-right"> 
      <tbody> 
        <tr> 
          <td class="col-lg-1 col-md-1 col-sm-1 col-xs-1 text-center"> 
            <div class="checkbox M0 marginTB10"> 
              <label class="M0 MT5 vibrate"> 
                <input type="checkbox" onclick="inver_checkbox(&quot;del_dialogs&quot;);" value="" class="vibrate"> 
                <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span> 
              </label> 
            </div> 
          </td> 
          <td class="col-lg-11 col-md-11 col-sm-11 col-xs-11"> 
            <div class="btn-group"> 
              <button type="submit" class="btn btn-danger btn-sm vibrate"><span title="Ваше сообщение" class="glyphicon glyphicon-remove"></span> Удалить </button> 
            </div> 
          </td> 
        </tr> 
      </tbody> 
    </table> 
    <div class="table-container"> 
      <table class="table table-filter-msg"> 
        <tbody> 
          <tr> 
            <td class="VAM col-lg-1 col-md-1 col-sm-1 col-xs-1 text-center"> 
              <div class="checkbox M0"> 
                <label class="M0 vibrate"> 
                  <input type="checkbox" name="del_dialog_one[]" value="22" class="vibrate"> 
                  <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span> 
                </label> 
              </div> 
            </td> 
            <td class="col-lg-1 col-md-1 col-sm-2 col-xs-2"> 
              <a href="/dialog/22/" class="vibrate"> 
                <img class="media-photo" src="/images/avatar/113f51ef4b8c25e81a54736d0337db75.jpg"> 
              </a> 
            </td> 
            <td class="col-lg-8 col-md-8 col-sm-6 col-xs-5"> 
              <div class="media"> 
                <a href="/dialog/22/" class="vibrate"> 
                  <div class="title pull-left"><strong>elmuza193</strong></div> 
                  <div class="clearfix"></div> 
                  <div class="">test в дар, 3 мес.</div> 
                  <p class="summary"> 
                    <span class="text-muted">dsfdfd</span> 
                  </p> 
                </a> 
              </div> 
            </td> 
            <td class="col-lg-2 col-md-2 col-sm-3 col-xs-3 text-right"> 
              <div class="text-muted FS12">08.04.2017 18:03</div> 
            </td> 
          </tr> 
          <tr> 
            <td class="VAM col-lg-1 col-md-1 col-sm-1 col-xs-1 text-center"> 
              <div class="checkbox M0"> 
                <label class="M0 vibrate"> 
                  <input type="checkbox" name="del_dialog_one[]" value="23" class="vibrate"> 
                  <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span> 
                </label> 
              </div> 
            </td> 
            <td class="col-lg-1 col-md-1 col-sm-2 col-xs-2"> 
              <a href="/dialog/23/" class="vibrate"> 
                <img class="media-photo" src="/images/avatar/113f51ef4b8c25e81a54736d0337db75.jpg"> 
              </a> 
            </td> 
            <td class="col-lg-8 col-md-8 col-sm-6 col-xs-5"> 
              <div class="media"> 
                <a href="/dialog/23/" class="vibrate"> 
                  <div class="title pull-left"><strong>elmuza193</strong></div> 
                  <div class="clearfix"></div> 
                  <div class="">лорпа</div> 
                  <p class="summary"> 
                    <span title="Ваше сообщение" class="glyphicon glyphicon-share-alt"></span> <span class="text-muted">ggg</span> 
                  </p> 
                </a> 
              </div> 
            </td> 
            <td class="col-lg-2 col-md-2 col-sm-3 col-xs-3 text-right"> 
              <div class="text-muted FS12">08.04.2017 14:31</div> 
            </td> 
          </tr> 
          <tr> 
            <td class="VAM col-lg-1 col-md-1 col-sm-1 col-xs-1 text-center"> 
              <div class="checkbox M0"> 
                <label class="M0 vibrate"> 
                  <input type="checkbox" name="del_dialog_one[]" value="24" class="vibrate"> 
                  <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span> 
                </label> 
              </div> 
            </td> 
            <td class="col-lg-1 col-md-1 col-sm-2 col-xs-2"> 
              <a href="/dialog/24/" class="vibrate"> 
                <img class="media-photo" src="/images/avatar/5e522636a001a6f5e5b2ff3300f6d6e4.jpg"> 
              </a> 
            </td> 
            <td class="col-lg-8 col-md-8 col-sm-6 col-xs-5"> 
              <div class="media"> 
                <a href="/dialog/24/" class="vibrate"> 
                  <div class="title pull-left"><strong>Svetlana</strong></div> 
                  <div class="clearfix"></div> 
                  <div class="">gdfgfdgdfg</div> 
                  <p class="summary"> 
                    <span title="Ваше сообщение" class="glyphicon glyphicon-share-alt"></span> <span class="text-muted">uuu</span> 
                  </p> 
                </a> 
              </div> 
            </td> 
            <td class="col-lg-2 col-md-2 col-sm-3 col-xs-3 text-right"> 
              <div class="text-muted FS12">08.04.2017 14:48</div> 
            </td> 
          </tr> 
          <tr> 
            <td class="VAM col-lg-1 col-md-1 col-sm-1 col-xs-1 text-center"> 
              <div class="checkbox M0"> 
                <label class="M0 vibrate"> 
                  <input type="checkbox" name="del_dialog_one[]" value="25" class="vibrate"> 
                  <span class="cr"><i class="cr-icon glyphicon glyphicon-ok"></i></span> 
                </label> 
              </div> 
            </td> 
            <td class="col-lg-1 col-md-1 col-sm-2 col-xs-2"> 
              <a href="/dialog/25/" class="vibrate"> 
                <img class="media-photo" src="/images/avatar/113f51ef4b8c25e81a54736d0337db75.jpg"> 
              </a> 
            </td> 
            <td class="col-lg-8 col-md-8 col-sm-6 col-xs-5"> 
              <div class="media"> 
                <a href="/dialog/25/" class="vibrate"> 
                  <div class="title pull-left"><strong>elmuza193</strong></div> 
                  <div class="clearfix"></div> 
                  <div class="">dfdfds</div> 
                  <p class="summary"> 
                    <span title="Ваше сообщение" class="glyphicon glyphicon-share-alt"></span> <span class="text-muted">gfdgfdgf</span> 
                  </p> 
                </a> 
              </div> 
            </td> 
            <td class="col-lg-2 col-md-2 col-sm-3 col-xs-3 text-right"> 
              <div class="text-muted FS12">08.04.2017 14:30</div> 
            </td> 
          </tr> 
        </tbody> 
      </table> 
    </div> 
  </form>