Add Days To Date Entered In Text Box

I want to create a function that will take a date that has been entered in to text box 1 and a number of days.

The function should take the date value passed in from text box 1 convert it from a string to a date format and add the number of days passed in to the function to the date then output that value in the format dd/mm/yyyy to a second text box.

So far I have:

Text box that fires the function onBlur
<input type="text" name="txt_ad_date" value ="" onBlur="addDays(26/01/2006, 1)">


The function
function addDays(myDate, days) {
adDate = new Date(myDate);
adDate.setDate(adDate.getDate() + days);
document.frmPermVacReq.txt_closing_date.value = adDate;
}

This should result in
07/02/2006 in text box 2 (txt_closing_date)

what I actually get is Fri Jan 2 00:00:00 UTC 1970

Any Ideas???