I am using Simple Commerce in conjunction with PayPal to sell subscriptions. Upon a successful transaction, PayPal sends an IPN back to the designated url to EE and the purchase is registered on the site and the member is moved to another member group.
The problem is that it does not always work. About 30% of the time the member is not moved to another group and the transaction is not reflected in Simple Commerce. In cases where it has failed, I checked PayPal and the IPN is shown as being sent, with the proper user id (in the custom field) and an HTTP 200 was sent back to PayPal, which would suggest EE acknowledgement of the IPN.
I looked at the Simple Commerce code and it seems to respond with a 200 even in cases where the Simple Commerce IPN handler deems the IPN as “invalid”, so no clues there.
I am at a loss to explain why it would work most of the time, but fail intermittently. Any suggestions on how to troubleshoot this would be appreciated!
Roi