Need help with a "getField" script!

Background:

I have a datefield (which is, on document load, automaticly gets the current date).
You can edit this field and put in desired date if you want to.

The field name is: "Date1"

SCRIPT FOR "Date1":

var f = this.getField("Date1");
f.value = util.printd("yy/mm/dd", new Date());

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I also have a field which you can put in a desired number of days.
The field name is: "Add_days"

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And finally I have a datefield which add the input value of the "Add_days"-field and calculates it to a new date. The script is a "Custom calculation script".
The field name is: "Date2"

SCRIPT FOR "Date2":

var sDate1 = "Date1";
var sAdd_days = "Add_days";

var nAdd = this.getField(sAdd_days).value;

var sDateFmt = 'yy/mm/dd';

var sDate = this.getField(sName).value;
var oDate = util.scand(sDateFmt, sDate);

var nFullYear = oDate.getYear();
var nMonth = oDate.getMonth();
var nDate = oDate.getDate();
nNewDate = nAdd + nDate;

var oNewDate = new Date(nFullYear, nMonth, nNewDate);
var sNewDate = util.printd(sDateFmt, oNewDate);
event.value = sNewDate;

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This is what I need help with:

I want the default value of "Date2", to be a slave to the value of "Date1"-field. So if the value of "Date1" is changed, the value of "Date2" also shall change.

I think its a very quick fix whith the "this.getField" script, but I cant get it to work.

Thanks for the help you guys!