glyphicon glyphicon-fullscreen not working

I have downloaded gentellela bootstrap template http://ift.tt/2srOT5B

Then I found

<!-- /menu footer buttons -->
                <div class="sidebar-footer hidden-small">
                    <a data-toggle="tooltip" data-placement="top" title="Settings">
                        <span class="glyphicon glyphicon-cog" aria-hidden="true"></span>
                    </a>
                    <a data-toggle="tooltip" data-placement="top" title="FullScreen">
                        <span class="glyphicon glyphicon-fullscreen" aria-hidden="true"></span>
                    </a>
                    <a data-toggle="tooltip" data-placement="top" title="Lock">
                        <span class="glyphicon glyphicon-eye-close" aria-hidden="true"></span>
                    </a>
                    <a data-toggle="tooltip" data-placement="top" title="Logout">
                        <span class="glyphicon glyphicon-off" aria-hidden="true"></span>
                    </a>
                </div>
                <!-- /menu footer buttons -->
            </div>
        </div>

When I click the icon of glyphicon glyphicon-fullscren or glyphicon-cog or glyphicon-eye-close or glyphicon-off, they are not showing. What may I do to fix that? For your information, I'm using Yii 2.0 framework. Thanks in advance