my guess is that this line is causing the problem:
<?php
//WA eCart Include
virtual("/WA_eCart/eCart1_PHP.php");
?>
the virtual() function will cause the header() function to fail with a "headers already sent" error.
in your site definition, there is a setting on the Local Info Tab titled "Create Links relative To:". if you select the "Server" option, Dreamweaver will use the virtual() function for attaching files. If you select the "Document" option, Dreamweaver will use the require_once() function instead.
I suggest using the A"Document" option.
change that code at line 1 - 4 to:
<?php
//WA eCart Include
require_once("WA_eCart/eCart1_PHP.php");
?>
if you contine to have a problem, add the following code to line 1:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
and see the following thread for details on the "headers already sent" error:
showthread.php?t=19285