Bootstrap中的Datepicker不会自动弹出

When I am clicking on the input field it only gets focus, but it doesn't show the datepicker unless I go at the extreme right corner of the field and click on the 'caret icon'. As this field attains focus, it should automatically popup the datepicker.

<div class="col-md-6">
    <h4>FROM DATE: </h4><input type="date" id="fd" name="fdate" class="form-    `        control" placeholder="Enter date" required> </input> 
</div>

I have included the bootstrap.css and bootstrap.js files.

Any ideas?