my applogies, this line:
if($WA_Store_Cart->GrandTotal() == 0) $WAGLOBAL_Test_Mode = true;
should be in the webassist/plugins/shopping_cart/cart_editable file.
change:
<?php
$WA_Store_Cart->GetContent();
?>
to:
<?php
$WA_Store_Cart->GetContent();
if($WA_Store_Cart->GrandTotal() == 0) $WAGLOBAL_Test_Mode = true;
?>