Ecart 6 checkout php intermittent error message

During testing on a remote server, getting an intermittent error when adding details to the form on checkout.php since it was initially created with the checkout wizard.

I have swapped the USA States select drop down for an Aussie one according to your advice in another forum post, but the error was occurring before that.

I can't find a similar issue in the forums, I think it might be related to validation.

The checkout.php file is attached as well as images.

Would you please check the page code attached. The site is www.busytest.biz

Additionally, the error validation is not preventing the "Please Wait" shadowbox from appearing when the Confirm Button is prematurely clicked.
The shadowbox then just hangs and I have to refresh.

Thanks for your help in this, sorry if I have made an error somewhere.

I'll need to troubleshoot directly, see the private message section.

Please see message in reply

I found an old version of the wavt_scripts_php.php file and an older jauery-blockui-formprocessing.js file

I updated both of them to the most recent version and the page works now

Thanks Jason, brilliant

you're welcome.