Can bus problem with multiple arduino

I have a project with 1 mega and 32 promini arduinos. I use for communication can-bus and mcp2515. I want mega arduino to send a message to prominies and take it back. But i have problems. When i send the messages i can take back the message at most 8 prominies. İ think there is a delay problem since when i change the delays, the number of yhe taken messages from prominies is changed. But i dont know what i must do. Any suggestion for this problem?