Paypal SandBox IPN always returns INVALID

Question

As mentioned in one of the comments in an answer below, I tried following this tutorial. So now I have the following:

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The ipn.php file:

Answer 1

Hours of hair pulling until I saw Izudin's answer. He's right..The + in the date wasn't being transferred. Just to test, I removed it from the pre-populated field in the simulator and got a Verified at last.