Javascript Different in CS3 vs. CSX?

Hi, is JavaScript different for acrobat verison CS3 Version 8 vs. X PRO - version 10?  I use online forms that users submit for clearance access.  I have been using Acrobat verison CS3, version 8, however, I recently updated to Acrobat X Pro and the script that I have doesn't work now.  The form itself still is fine, just the script for the textbox doesn't work.  The textbox indicates authorized signer status.  The form is locked after signing, except for this textbox which should be able to change...

I'm stumped..

Here is the script:

var digSig = event.target.getField("topmostSubform[0].Page1[0].AUTHORIZED_APPROVERS_SIGNATURE[0]");

var sigInfo = digSig.signatureInfo();

if (digSig) {

var status = digSig.signatureValidate();

var message = "";

switch (status) {

case 0:

case 1:

message = "NOT SIGNED";

break;

case 2:

message = "INVALID SIGNATURE";

break;

case 3:

message = "VALID BUT IDENTITY OF SIGNER CANNOT BE VERIFIED";

break;

case 4:

message = "VALID SIGNATURE";

break;

default:

message = "ERROR";

break;

this.rawValue = "SIGNATURE STATUS: " + message;

And here is the error message I receive when loading the form within acrobat.

Thank you kindly.