Segmentation fault error

Hello,

As I'm trying to built a communication between two terresterial nodes
via satellite using the DTN protocol and specefically unslotted aloha
as a mac protocol, I get this error : "segmentation fault  (core
dumped)" once this line is executed:$ns at 15 "$ftp0 send 1000000".
you will find my script file attached with this message.


I hope I can get some help with it,

Many thanks for considering my request.


more informations :
SPICE DTN Agent for ns-2
ns2.35
Ubuntu 14.04 LTS 64-bit