Telegram bot不接收转发的消息

I've created a telegram bot.
Everything works fine and I can receive updates.
Except for when you forward a message to it, it doesn't receive it.
any Ideas?

I have set the webhook and get updates like this:

$update = json_decode(file_get_contents('php://input'));  

after this, I process updates normally, but only direct messages arrive. and Forwarded messages dont.

Bots can not detect messages from other bots. some members forward message from bots then your bot can not receive it.