DatePicker doesn't work inside fixed div

DatePicker doesn't work inside fixed div

I tried putting DatePicker inside of a fixed position div that is attached to the bottom of the viewport. When clicking on the input box that should open the calendar, I see in Firebug that the dimensions of the calendar box slide out, but the box doesn't appear where it should above the input. Is this expected? I'm assuming there is some conflict with it being inside a fixed div. And is there any known way to use DatePicker from within a fixed div?