I am using this for select combo,After adding its css and Js files i got this result. Here what i have tried so far.
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.4/css/bootstrap-select.css"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.4/js/bootstrap-select.js"></script>
<select class="selectpicker show-tick form-control">
<option>pen</option>
<option>pencil</option>
<option selected>brush</option>
</select>
The output.
So can you please have a look at this why this is happening ?
Add the script to initialize bootstrap select