Why does a script work on FF and Chrome but not on IE

There’s this weird problem where the following script would work nicely on FF and Chrome but does not work on any version of IE. I tried to debug but no avail and hence seeking your help on this.

Succesful runs:

FF: WebPageTest Test - Running web page performance and optimization tests...
Chrome: WebPageTest Test - Running web page performance and optimization tests...

Failed Runs:
IE 11: WebPageTest Test - Running web page performance and optimization tests...
IE 9 : WebPageTest Test - Running web page performance and optimization tests...
IE 8: http://www.webpagetest.org/result/150302_AW_C14/[/quote]

Here’s my script

What gives on IE?

I tried this but it fails in IE too - so you might need to walk through the DOM scripting in IE

combineSteps
navigate	http://www.insight.com/
exec document.getElementById('searchText').value="hp laserjet pro"
execAndWait	document.getElementById('searchBtn').click()
execAndWait	document.getElementById('CE749AR#BGJ_^^HP LaserJet Pro P1606DN - printer - monochrome - laser - remarketed').click()
execAndWait	submitPPPSubmission('main', 'CE749AR#BGJ',false);
execAndWait	location.href = '/insightweb/viewCart';
exec	document.getElementById('j_username').value="keynoteuser1"
exec	document.getElementById('j_password').value="password1"
execAndWait	InsightNavigation.validateLoginSmallWindow();
execAndWait	callShipBillPayPage('shippingOrder');

One thing I did notice while looking at it is that a couple of the strings end with rather than

Might have another poke at it later if I get the chance

Let me know if you did. BTW this isnt unique to WebPageTest, I also had Catchpoint Support guys get caught up in the same issue (they use Selenium IDE etc) so definitely points to something on their site