you have a blank line between php code blocks at line 5, that needs to be removed, and the following code needs to be at line 1:
<?php
//WA eCart Include
require_once("WA_eCart/eCart1_PHP.php");
?><?php
$eCart1->GetContent();
?>
<?php
require_once("WA_eCart/PP_ECO_Scripts/PP_ECO_PHP.php");
?>