Bootstrap nav wouldn't close - html

Question

I know that there are other posts with the same subject, but I tried a lot of them but still got the problem.
I can perfectly open the nav, but when I want to close it, it just flicker, and it doesn't close at all.
<nav class="navbar navbar-default">
#*navbar navbar-default*#
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#menu-collapse" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<p class="hidden-sm hidden-md hidden-lg">#Model.Content.Name</p>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="menu-collapse">
<ul class="nav navbar-nav">
#foreach (var item in selection)
{
if (item.Children.Count() > 0)
{
<li class="dropdown #(item.Id == Model.Content.Id ? "current" : null)">
#item.Name.ToUpper()
<ul class="dropdown-menu">
#foreach (var child in item.Children)
{
<li class="#(item.Id == Model.Content.Id ? "current" : null)">
#child.Name.ToUpper()
</li>
}
</ul>
</li>
}
else
{
<li class="#(item.Id == Model.Content.Id ? "current" : null)">
#item.Name.ToUpper()
</li>
}
}
</ul>
</div><!-- /.navbar-collapse -->
Html.RequiresCss("/css/bootstrap.min.css", 1);
Html.RequiresCss("/css/bootstrap-responsive.css", 1);
Html.RequiresJs("https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js", 0);
Html.RequiresJs("/Scripts/bootstrap.min.js", 1);
I hope that someone know what can cause this error.