IPN response with 200 HTTP code but nothing in my database

[RomanoDome]

General information

Hi everybody, this is my first time here. I hope I do everything correctly (also, sorry for my English: I'm italian).
I really need help because I don't know what to do at this point. I'm using these files: "PaypalIPN.php" and "example_usage.php". I also added to my Ubuntu cloud server (where is my website) the cert/cacert.pem, I don't know if I had to do but in the first file seems to be required.

Issue description

I tried to run a IPN simulator but it doesn't work, I looked for the same problem and right here in github I found that there may be a problem with the simulator, so I made some real transactions (I've read that live production test is run correctly with that code).
Therefore:

• the transaction money is ok;
• in the Instant payment notification history there are all test I made and in message ID I can read the correct data passed in the IPN message, the IPN type is "Transaction executed" and the response code is 200. I noticed that in "example_usage.php" the 200 response code was out of the if ($verified) so, just for my last test, I put that inside the if and yes, the response was again that;
• I tried my code for update the mongodb database with fake data and obviously it works.

How is it possible? Please, help me and thank you.

[RomanoDome]

Solved: the directory (where are my ssl certificates) didn't have the permission for being read, so I changed the permissions with chmod.