This is a part of code from my nav bar. I am trying to create a dropdown menu, but unfortunately on mobile when i click the toggle instead of showing dropdown it closed . I have tried to update all the stylesheet bootstrap code , and link . i have tried other models on navbar dropdown but the same thing
<nav class="navbar navbar-expand-lg">
<a class="navbar-brand" href="index.html">
<img src="assets/images/mindnmovelogo.png" alt="Logo">
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="toggler-icon"></span>
<span class="toggler-icon"></span>
<span class="toggler-icon"></span>
</button>
<div class="collapse navbar-collapse sub-menu-bar" id="navbarSupportedContent">
<ul id="nav" class="navbar-nav ml-auto">
<li class="nav-item">
<a class="page-scroll" href="#home">INDUSTRIES</a>
</li>
<li class="nav-item">
<a class="page-scroll" href="#about">WHO WE ARE</a>
</li>
<li class="nav-item dropdown">
<a class="page-scroll nav-link " href="#" id="navbarDropdown" data-toggle="dropdown"
aria-haspopup="true" aria-expanded="false"><i class="fa fa-newspaper-o"></i>WHAT WE DO</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="#">Link 1</a>
<a class="dropdown-item" href="#">Link 2</a>
</div>
</li>
<li class="nav-item">
<a class="page-scroll" href="#footer">GET IN TOUCH</a>
</li>
</ul>
</div> <!-- navbar collapse -->
<div class="navbar-btn d-none d-sm-inline-block">
<a class="main-btn" data-scroll-nav="0" href="mailto:">GET A FREE QUOTE</a>
</div>
</nav> <!-- navbar -->