IPN Call back not logging Pledges


Could you help out. I have looked at responses on the forum to this same issue but with no success.
When a pledge is made it process through paypal but does not register the pledge.
We keep getting a 503 :-
"Oh No, we can't find your Pledge. Sometimes it take a few moments for your Pledge to be logged. You can try refreshing this page"
I have put this on a test server, tired removing all plugin, removing the theme so it is just a basic set up but still have the same issue.

Can you have a look at the settings - I have granted support access.

Thanks for your help