Libtins Sender does not send all packets from Sniffer

[Anna]

I'm using libtins and i want to create a sniffer, that sends every packet received on eth1 to eth2:

bool callback(PDU &pdu) 

 {

  PacketSender sender("eth2"); 

 sender.send(pdu); return true; 

 } 

 int main() {

    SnifferConfiguration config; 

    config.set_immediate_mode(true); 

    config.set_promisc_mode(true); 

     config.set_direction(PCAP_D_IN); 

    Sniffer s1("eth1", config); 

    s1.sniff_loop(callback); 

    }

The Sniffer works, but it does not send all packets to eth2. I#m sending ipv6 UDP Packets and SOME/IP Packets. Some of them are sent to eth2, some are not. But no no pattern recognizable. Can you help me to fix this?