set limit to date field

Well, for starters, the two scripts discussed in part 1 don't work, at least not on my computer. The first one returns an error message of "theNewDate is not defined", and the second returns an error message of "strMessage is not defined". In part 2, Mr. Parker states that the "Order Date" field of his attached form has been set to "read only" when in fact it has not, and states that the 3rd line of his script should be "if(strStart.length || strEnd.length)" while his attached form says "if(strStart.length && strEnd.length)". The script in part 2 seems to work in his attached form, but when copied directly from part 2 into the console in Acrobat on my computer returns an error of "days is not defined". Clearly Mr. Parker's tutorials are riddled with typos.

This is the (successful) script in my first date field:

var date = util.scand("mm/dd/yyyy", this.getField("certDate").value);
var expire = this.getField("expireDate");

date.setDate(date.getDate()+730)
if (this.getField("certDate").value!="")
{
expire.value = util.printd("mm/dd/yyyy",date)
}
else
{expire.value = ""}

This is the (unsuccessful) validation script in my second date field:

var strStart = this.getField("certDate").value;
var strEnd = this.getField("expireDate").value;

if(strStart.length || strEnd.length) {

var dateStart = util.scand("mm/dd/yyyy",strStart);
var dateEnd = util.scand("mm/dd/yyyy",strEnd);

var diff = dateEnd.getTime() - dateStart.getTime();

var oneDay = 24 * 60 * 60 * 1000;

var days = Math.floor(diff/oneDay);

if (days.value > 730) {
app.alert("The expiration date cannot be more than two years later than the certificate signature date.");
}
}