Problem starting a python program with OpenWrt Linkit7688

Hi, I have a problem when executing a program made in python
for a linkit 7688, when starting. I made a script so that the
startup executes the program in the path /etc/init.d/startup.
Boot the linkit card with openwrt os, run the program.
Which use a serial port, and after a few minutes the program crashes.
The same program works fine, if I wait it to load the whole system
and type admin-> root and the password -> *****
what could be the problem?