Error in the log file with PayPal payment - virtuemart 3.0.16

[antonino78]

Hello, I received an order with Paypal payment.
The mail order detail I did not arrive in the backend and the rusulta order on hold.
Right after I got this email with the following message:
Hello, an error with the PayPal payment method on your store (store name). Details are recorded in paypal.4.log.php file. the VirtueMart team "
in the log file there is only this string:
#
# <? Php die ( "Forbidden."); ?>

04/17/2016 15:42:04 ERROR validateIpnContent: IPN Validation incorrect: NO ANSWER FROM PAYPAL

This error came after the user canceled the payment twice.
The third time has confirmed the order and payment, but the order is in a state of "pending"

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