The eCart Display wizard is installing this on the page:
<form action="<?php echo ($_SERVER["PHP_SELF"].(isset($_SERVER["QUERY_STRING"])?"?".htmlentities($_SERVER["QUERY_STRING"]):""));?>" method="post">
Which is trying to submit to /dreamcaruk/view-cart.php.
I can't open the checkout button behaviour to edit this, nor do I know what it should actually be. Can you help with this?