network latency on specific port is invalid

[zhqqqy]

when I use this command

./comcast --device=eth0 --latency=5000 --target-proto=tcp,udp,icmp --target-addr=10.215.45.5

it is useful.but if i add --target-port=9999 like

./comcast --device=eth0 --latency=5000 --target-proto=tcp,udp,icmp --target-addr=10.215.45.5 --target-port=9999

it doesn’t work .

system CentOS release 6.9 (Final)
Comcast version 1.0.0