Loading View with Posting Data

In your edit.php (view) you are generating a form with these attributes:

Code:

<form action="" method="post" id="date_picker_form">

Because of the action="", the input is posted to the same url that was used to call the form.
Maybe I'm wrong, but as far as I can see, the form is generated from the National method first. If you submit your form, the data is posted to the National method again, and I think that's where you are going wrong.