the problem is that the line to include the eCart file is missing from your page.
change:
<%@LANGUAGE="VBSCRIPT"%>
<!--#include file="WA_eCart/WA_eCart_Database_VB.asp" -->
to:
<%@LANGUAGE="VBSCRIPT"%>
<!--#include file="WA_eCart/WA_eCart_Database_VB.asp" -->
<!--#include file="WA_eCart/ultimate_Air_Vent_Cart_VB.asp" -->