Cannot send push via APNS: 403 Forbidden

Hello experts,

I have a problem to push notification to SMP registered application. The application is registered. Push settings are setup. APNS parameters as <d:ApnsPushEnable> and <d:ApnsDeviceToken> are set.

My call is a POST to push URL with X-SMP-APNS-ALERT-LOC-KEY & X-SMP-APNS-ALERT-LOC-ARGS as headers and I am receiving 403 Forbidden:

Is that means that my APNS certificate is invalid? I will appreciate every answer, advice, recommendation.

Thank you in advance,

Dimiter