SimpleAudioEncoder Does Nothing

I am working on AAC encoder for one of my projects and I am trying to implement SimpleAudioEncoder from AVCodecs.

Getting raw audio from submix buffer, encoder initialization and configurations are okay. But Encoder->ReceivePacket returns 0.

I checked codes and there is nothing in AVCodecs AudioEncoder.cpp

If AVCodecs Encoder didn’t finished, is there any estimation for it ?
(even rough estimations ?)