Error: TypeError: $(...).dialog is not a function

I am having an issue getting a dialog to work as basic functionality. Here is my jQuery source imports:

<script type="text/javascript" src="scripts/jquery-1.9.1.js"></script>
<script type="text/javascript" src="scripts/jquery-ui-1.11.1.js"></script>
<script type="text/javascript" src="scripts/json.debug.js"></script>

Html:

<button id="opener">open the dialog</button>
<div id="dialog1" title="Dialog Title" hidden="hidden">I'm a dialog</div>

<script type="text/javascript">
    $("#opener").click(function() {
            $("#dialog1").dialog('open');
    });
</script>

From the posts around seems like as a library import issue. I downloaded the JQuery UI Core, Widget, Mouse and Position dependencies.

Any Ideas?