PayPal IPN error!!!

Hi,

We were using paypal plugin in sandbox mode, which worked fine for the recurring payments. We changed it to live one (with proper ipn changes) . We did a test transaction from a live paypal account. In admin logs, we are getting the following error :

IPN seems to be received from unknown source, not from the paysystem

following is the log details for this invoice :

<invoice-log-item type="incoming-request">
<url>
<method>POST</method>
<scheme>http</scheme>
<base_url/>
<path_info>/payment/paypal/ipn</path_info>
<host>www.churpee.com</host>
<remote_addr>173.0.81.1</remote_addr>
</url>
<params>
<param name="transaction_subject">New Churpee Operator (single additional user): $9.99 per month</param>
<param name="payment_date">22:53:18 Jan 03, 2013 PST</param>
<param name="txn_type">subscr_payment</param>
<param name="subscr_id">I-51F9JRY6RCBH</param>
<param name="last_name">Ramamurthy</param>
<param name="residence_country">IN</param>
<param name="item_name">New Churpee Operator (single additional user): $9.99 per month</param>
<param name="payment_gross">9.99</param>
<param name="mc_currency">USD</param>
<param name="payment_type">instant</param>
<param name="protection_eligibility">Ineligible</param>
<param name="verify_sign">AYMDpR.hfL0yfpu7kcWv1wHkJpJaAzUhEs8JWX6YKBf6XVrp4NMGdSa3</param>
<param name="payer_status">unverified</param>
<param name="payer_email">external@convonix.com</param>
<param name="txn_id">1UH72877KM2188849</param>
<param name="receiver_email">sam@thesearchcafe.com</param>
<param name="first_name">Shivakumar</param>
<param name="invoice">J0G9Y</param>
<param name="payer_id">5CLEGYJS863KS</param>
<param name="receiver_id">U5QSGE36KCUL4</param>
<param name="payment_status">Completed</param>
<param name="payment_fee">0.79</param>
<param name="mc_fee">0.79</param>
<param name="mc_gross">9.99</param>
<param name="charset">windows-1252</param>
<param name="notify_version">3.7</param>
<param name="ipn_track_id">c3f9a88d94a5</param>
</params>
</invoice-log-item>



Kindly advice what has gone wrong?

As required :

Exception Am_Exception_Paysystem_TransactionSource
Am_Paysystem_Transaction_Incoming->validate [ library/Am/Paysystem/Transaction/Abstract.php : 48 ]
Am_Paysystem_Transaction_Abstract->process [ library/Am/Paysystem/Transaction/Incoming.php : 231 ]
Am_Paysystem_Transaction_Incoming->process [ library/Am/Paysystem/Abstract.php : 452 ]
Am_Paysystem_Abstract->directAction [ application/default/controllers/DirectController.php : 29 ]
DirectController->__call [ library/Am/Controller.php : 118 ]
Am_Controller->dispatch [ library/Zend/Controller/Dispatcher/Standard.php : 295 ]
Zend_Controller_Dispatcher_Standard->dispatch [ library/Zend/Controller/Front.php : 954 ]
Zend_Controller_Front->dispatch [ library/Am/App.php : 1596 ]
Am_App->run [ index.php : 43 ]