I am trying to use this: to parse this:

<?xml version="1.0" encoding="utf-8"?>
<PaymentNotification xmlns="http://">

…but can’t work out which numbers to use. I only need to grab the payment ID where the statusID is 4 (for each one as could be 1 or more per xml message).

It’s very complicated

Do you absolutely need to use that function? It’s a pretty ancient and convoluted way of accessing XML in PHP.