Google Analytics tracking code interfering with form submission

Hi

Have been investigating issues with our contact form http://www.lmkthermosafe.co.uk/request-quote/

The form is working – data is submitted correctly to us – but on hitting the submit button, there is no on-screen confirmation of successful submission and the form does not clear down. Consequently users are confused and tend to re-submit.

Have isolated the problem to the tracker code we were given by Google Analytics to monitor ad word conversions. We added this to the Additional Settings tab:

on_sent_ok:”_gaq.push([‘_trackEvent’,’form’, ‘submit’, ‘contact us’ ])”

Am guessing this has interfered with submission javascript?

Any help would very much appreciated.