Libtins Sender does not send all packets from Sniffer

[annagrunow]

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?