using arpspoof on virtualbox (BT5r3 over osx 10.8.2) i got a strange problem: if i try to poison a single client A, from a client B, wireshark doesn't show me any arp packet. (why?)
If i try to poison in broadcast: wireshark, on the client A, shows me the right arp packets and the arp table of the client A it's filled correctly with the client B mac address linked to the gateway IP.

The point is: i'm trying to ping the gateway from client A, wireshark (on client A too) shows me icmp packets but the mac address is of the "original" gateway and not of the client B. The arp table of the client A is still filled rightly.

Some suggestion?