I am working on a custom payment system for my blog (PHP), and now I am trying to implement the IPN system.
I have fully copied the PayPal php example, but no matter what I do, I always get an INVALID response when validating the IPN request.
I have read tons of other topics explaining the same problem and still can't find a solution.
- I am using the OFFICIAL code example
- I am using the sandbox IPN address
- I have tried with and without setting a value in 'payment_date' , because many others suggested that the problem is in the plus sign inside the date.
- Tried with and without https:// at my end
- I have tested the code on 2 different servers, from 2 different PayPal developer accounts.
And each and every time the response of the validation is INVALID.
I am almost ready to give up...
Thanks in advance!
