Hi,
i use blackberry messenger with a friend. When i chat with him, He receive my chat but when he answer me, i have nothing. Someone can help me please.
Me Curve 8310 OS 4.2
Him 8100 OS 4.2
Together on different BES.

Your BES might have BB Messagenger receipt disabled?

Can you send and receive PIN messages in the Message folder?

hi,
i tried me if i sent a pin he receive, but he can't answer me. On he's 8100 it's notify that it's sent but i receive nothing.

Try testing this by the PIN message. Message folder > menu > Compose PIN.

Can either of you send to the other a PIN message and the other receive it?

One, or both, of your BES probably has a peer-to-peer encryption key set up.
If so, then you can only use PIN and BB messenger with users on the same BES.