Yahoo Maps API - Same code ok in Firefox, not IE7 - asp.net

Question

I've implemented a simple yahoo mapping example using JQUERY.
My problem is i'm developing using my localhost, my intended target platform is to be within an Intranet environment. My thinking is that my localhost will to some extent mimic this.
I have an update, made some progress. See the code snippet below, all ok in Firefox but in IE (my target browser) it fails on the line:
var currentGeoPoint = new YGeoPoint($('#txtLatitude').val(), $('#txtLongitude').val());
What I cannot understand is why will IE allow the MAP API Code to run and manipulate the MAP object and fail on this one line.
Could this all be to do with Tools/Intranet Options/Security and trusted sites etc? My URL locally is "http://localhost:4724/LMS/Site.mvc/Details/77" if thats any help.
$(document).ready(function() {
jQuery("textarea[class*=expand]").TextAreaExpander(); // initialize all expanding textareas, new code, john s 10/08/2010
var geoPoint;
// Create a map object
var map = new YMap(document.getElementById('map'));
// Add map type control
map.addTypeControl();
// Set map type to either of: YAHOO_MAP_SAT, YAHOO_MAP_HYB, YAHOO_MAP_REG
map.setMapType(YAHOO_MAP_REG);
// Display the map centered on a geocoded location
map.drawZoomAndCenter("United Kingdom", 12);
// Add map type control
map.addTypeControl();
// Add map zoom (long) control
map.addZoomLong();
// Add the Pan Control
map.addPanControl();
// Set map type to either of: YAHOO_MAP_SAT, YAHOO_MAP_HYB, YAHOO_MAP_REG
map.setMapType(YAHOO_MAP_REG);
// Display the map centered on a geocoded location
map.drawZoomAndCenter("United Kingdom", 12);
var currentGeoPoint = new YGeoPoint($('#txtLatitude').val(), $('#txtLongitude').val()); // FAILS IN IE ON THIS LINE!! Unspecified Error popup dialogue box
map.addMarker(currentGeoPoint);
});
John

Answer 1

Have this working now, reverted back to original javascript, i'd hand rolled my own code and although neater was not working in IE. Glad to be out of the woods, cheers, J