Vista - calender popup control + asp.net

hi i need ur help as you have worked on calendar popup control ,i
want ur help in my application . i have used popup calendar and in my
regional language and services i have set date format as dd/mm/yyyy.
so calendar also takes the same date . But when i create a virtual
directory of my application folder (with web sharing ) the calendar
takes date format as MM/dd/yyyy . why dose this happen . i want the
date in the format dd/mm/yyyy.
plz suggest me some solution .
thanks in advance .