After some problems solved, I got a tricky stuff. I am using an overlay plugin for JQuery called prettyPhoto.
Just wanna make an overlay with a form. The form is hid
after looking into your codes, here's what I found.
It seems that you binded the datepicker correctly on the popup form. The problem is, when you initialize the prettyphoto, the binded datepicker is not anymore binded. If you can look at firebug and watch closely on , that's where your form goes. What happen now, is when you open/close the popup, the form gets remove or added to the DOM. That's the problem.
One solution I can think is for you to use another overlay plugin.