无法将php服务器连接到apple apns

I am developing an app in which apple push notification service is using. I downloaded an ssl certificate and bind it with private key (in keychain) and convert it in .pem format for php server . But when am going to connect to apns through php by providing .pem certificate and pass-phrase and device token it gives me an error Failed to connect. I tried sending push notification using PushMeBaby application in that case am able to receive notification. But why failed to connect from php server .... Please help me to resolve this problem..I am developing an app in which apple push noti