Dynamica Counting Stamps

There is one obvious problem here: You are comparing the typeof your counter variable with the name of your stamp - these two things have nothing to do with each other. In the original script, the line

if(typeof(oDoc.stampCounter) == "undefined")

is trying to determine if the variable has been created. If it does not exist yet, then the next line

oDoc.stampCounter = 0;

will initialize it to zero.

You need to go back to the dynamic stamp basics to get a better understanding of how dynamic stamps work. The best way to learn is Thom's book: http://www.pdfscripting.com/public/All-About-PDF-Stamps-in-Acrobat-and-Paperless-Workflows-The-Book.cfm

Is the JavaScript you've posted your whole script? If so, there is a lot missing that is necessary to create a dynamic stamp.

Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com

You would need something like this as your calculation script for the calculated form field. You would have to change the stampName in the first line to match your stamp name:

if( event.source.forReal && (event.source.stampName == "#NumberStamp"))
{
    var oDoc = event.source.source;
    if(typeof(oDoc.stampCounter) == "undefined")
        oDoc.stampCounter = 0;

    oDoc.stampCounter++;
    event.value = oDoc.stampCounter;
}

Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com