If you've got all the plugin JS's imported and in the correct order, but you're still having issues, it seems that specifying your own "add" handler nerfs the one from the *-validate.js plugin, which normally would fire off all the validation by calling data.process(). So to fix it just do something like this in your "add" event handler:
$('#whatever').fileupload({
...
add: function(e, data) {
var $this = $(this);
data.process(function() {
return $this.fileupload('process', data);
}).done(function(){
//do success stuff
data.submit(); <-- fire off the upload to the server
}).fail(function() {
alert(data.files[0].error);
});
}
...
});