Using jquery.validate and jquery-ui

Using jquery.validate and jquery-ui

As lines below, only works the datepicker.
Why is not working both validate and datepicker?
Thank you for your help.
Obs .: If you need more code to details, I can post.

<! - Validate ->
<script type = "text / javascript" src = " http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.9.0.min.js"> </ script>
<script type = "text / javascript" src = " http://ajax.aspnetcdn.com/ajax/jquery.validate/1.9/jquery.validate.min.js"> </ script>

<! - Datepicker ->
<link rel = "stylesheet" href = "// code.jquery.com/ui/1.9.0/themes/base/jquery-ui.css">
<script src = " http://code.jquery.com/jquery-1.8.2.js"> </ script>