IPN: error - Subscription Error

The following error message was generated while trying to acknowledge IPN:

        Notification received was NOT from PayPal - Message was ignored. http://www.paypal.com/cgi-bin/webscr: INVALID

User Information

	Subscriber's Username: pp-chunkkind
	Subscriber's Email: klip(*)testcustomer.com
	Subscription Number: S-2ES736416S834110J
	Transaction Type: subscr_payment

Query:txn_type=subscr_payment&payment_date=03%3A07%3A45%20Aug%2023%2C%202007%20PDT&subscr_id=S-2ES736416S834110J&last_name=Rogers&option_selection1=east3rd&residence_country=CA&pending_reason=echeck&item_name=Arkiv%20Membership%20Fee&payment_gross=&mc_currency=CAD&business=service%40testcompany.com&payment_type=echeck&verify_sign=AD8kCEkfgchvclccKrC.h.iL.FBkANP3xRGMFrjmjhZSgtVkqrCX2Jaj&payer_status=verified&test_ipn=1&payer_email=klip%40testcustomer.com&txn_id=02P418921Y318052F&receiver_email=service%40testcompany.com&first_name=Klip&option_name1=account&payer_id=RP5LPT45BTH82&receiver_id=NVZBFVWF6XPEG&password=DQL9RQec%2FF%2FGg&item_number=001&payment_status=Pending&mc_gross=9.95&username=pp-chunkkind&charset=windows-1252&notify_version=2.4 Received on Thu Aug 23 2007 - 06:08:01 EDT