libnet_write_raw_ipv4() Message too long

Hello,

i have a problem with my libnet application. I have written a small programm to test my firewall and a packetlogger. My code simply creates some ip packets with valid ip addresses in a loop. 
Those packets are transmitted via tcp.

Everything works fine for about 70 packets, then i get the (Message too long) error msg.

The problem is that my code always adds the data for the new packet to the current libnet context. I need a way to get rid of the old data after i have sended a packet in a loop.

pseudo code:

while (ip addresses)