something seems wrong with your jQueryUI file . Page is throwing "datepicker is not a function" error
try using this cdn version as your src for jQuery UI
EDIT: I forgot, when you download custom version of jQuery UI you elect which components you want.
Looks like you didn't include datepicker. You probably don't have css for it either then
CDN above is full jQuery UI js, so datepicker is in it, you may need addiditonal css resources though also