My app is still in development and I used this tutorial to send iOS Push Notifications using PHP and SSL.
http://www.raywenderlich.com/32960/apple-push-notification-serv
Here are a few tips that should can help you figure out:
Go to entrust.net/downloads/root_request.cfm and download entrust_2048_ca.cer
Add following code: stream_context_set_option($ctx, 'ssl', 'cafile', 'entrust_2048_ca.cer');
Make sure if path is right: '../folder/file/ck.pem' ?
Switch and try both the sandbox and live ssl links.
Switch dev and production pem and try both.