Ваш формат должен быть таким: "DD/MM/YYYY"
$(function() {
$('#DateOfBirth').datetimepicker({
format: "DD/MM/YYYY"
});
});
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://cdn.rawgit.com/Eonasdan/bootstrap-datetimepicker/e8bddc60e73c1ec2475f827be36e1957af72e2ea/build/css/bootstrap-datetimepicker.css" rel="stylesheet"/>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.9.0/moment-with-locales.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datetimepicker/4.17.37/js/bootstrap-datetimepicker.min.js"></script>
<div style="position: relative">
<input type="text" id="DateOfBirth" class="form-control" />
</div>
да правильно. теперь все в порядке. благодаря –