start and end date validation for searches [SOLVED]

[eluser]tim1965[/eluser]
Hi

I am struggling with a couple of issues around form validation. This is my first website. I have a search form that allows a user to specify a start and end date for searching using jquery datepicker in the format dd/mm/yyyy. So my first problem is how to ensure that the end date is set before allowing the search to proceed using form validation and also whether i need to validate the date beyond just xss clean and trim. I could probably do this using Jquery but want to ensure it is also done in PHP using CI´s form validation library. I am guessing i need some form of callback but am absoloutely stumped as to how to do this.

My second issue is kind of tied around the first. I have a third field that is dependant on the start and end date parameters being set. I hide this and only display on input to start and end date using jquery, but once again want to make sure i have this covered in CI as well.
Thanks in advance for any help.