[Twisted-Python] question : SerialService and an autostart application of autologin user, strange behaviour

[bino oetomo]

Dear All ..

My system is an ubuntu box with openbox and Slim.

in my tac file with a SerialService, I have this line

serial = SerialPort(ArduinoReceiver(), '/dev/arduino', 
reactor,baudrate=4800)

This tac file always run well when I start it manualy from xterm.
I call it using an sh script :

--> startcore.sh &

#!/bin/bash
twistd -ny /opt/sikat/scripts/core11.tac -l 
/opt/sikat/scripts/core11.log --pidfile /opt/sikat/scripts/core11.pid


Next ... I try to call that script from my openbox autostart.sh 
(/home/sikat/.config/autostart.sh) :
/opt/sikat/scripts/startcore.sh &
/opt/sikat/bin/navit &

This way I want that whenever the system is booted,
'sikat' is autologed in by slim, and
my twistd tac script is started by openbox's autostart

THe result is :
1. twistd tac file is started,
2. No error log complaining about serial port, but
3. Anything send by my arduino looks like did not received by TAC script.

Kindly please tell me how to (what to look for to) fix this problem

Sincerely
-bino-