KnockoutJS : Unable to process binding "if: function (){return conversations }"

First, here's my view

<div data-knockout="messenger-block">
<div id="messenger-attachment-container" class="container-messenger">
    <div style="display:none" data-bind="visible: conversations().length > 0">
    </div>
</div>
<div id="messenger-dialog-container" class="container-messenger-bottom">
    <div data-bind="visible: conversations().length > 0, if: conversations">
    <!-- ko foreach: conversations -->
        <div class="display-discussion-block object-shadow-near">
            <div class="display-discussion-header"> <!-- Quand un nouveau message appliquer la classe .display-discussion-header-active -->
                <div data-bind="if: receiver">
                    <div class="display-avatar object-shadow-near"
                         data-bind="style: { backgroundImage: 'url(' + receiver().profilePicture.url + ')' }">
                    </div>
                </div>

                <div class="status connected"></div>
                <a href="#">
                    <div data-bind="if: receiver">
                        <span data-bind="text: receiver().firstname"></span> <span data-bind="text: receiver().lastname"></span>
                    </div>
                </a>

                <button class="btn-options messenger-popover-action"></button>
                <div class="popover-standard messenger-options" style="display:none; margin-left : -80px; margin-top : 21px;">
                    <ul>
                        <li class="attach-detach">Attacher</li>
                        <li>Afficher la conversation complète</li>
                    </ul>
                </div>
            </div>
            <div class="container-discussion-body">
                <div class="container-discussion">
                    <div data-bind="if: conversation() && conversation().messages">
                    <!-- ko foreach: conversation().messages -->
                        <!-- ko if: ($index == 0 || sender.id != $parent.messages[$index].sender.id) -->
                            <!-- ko if: $index > 0 -->
                                    </div><!-- block-discussion -->
                                </div><!-- container-msg -->
                            <!--/ko-->
                            <div class="block-discussion">
                                <div class="container-msg">
                        <!--/ko-->
                        <div data-bind="css: $parents[1].blockMessageClass(sender.id)">
                            <span data-bind="text: content"></span>
                        </div>
                        <!-- ko if: $parents[1].appUser().id == sender.id -->
                            <div style="clear:both"></div>
                        <!--/ko-->
                    <!--/ko-->
                            </div>
                        </div>
                    </div>
                </div>
            </div>
            <div class="container-submit">
                <form>
                    <div class="form-group">
                        <textarea class="form-control" data-toggle="submit-enter" placeHolder="Répondre quelque chose.." rows="1"></textarea>
                        <div class="block-icons">
                            <div class="icons icon-add-img"></div>
                            <div class="icons icon-add-smiley"></div>
                        </div>
                    </div>
                </form>
            </div>
        </div>
    <!--/ko-->
    </div>
</div>

Everything work, but when i add these lines :

<!-- ko if: $index > 0 -->
        </div><!-- block-discussion -->
    </div><!-- container-msg -->
<!--/ko-->

I get the following error from my browser : "Error: Unable to process binding "if: function (){return conversations }" Message: Cannot find closing comment tag to match: ko foreach: conversations ".

I don't know why these lines in particular make the problem. If i put some , it just breaks.