Application auto-start at boot on WP8548(Firmware release14)

Hello, I want to start my application at boot by using /etc/init.d/
The problem is that only my application doesn’t start at boot.
(=In the following case, test.txt is generated, but my application doesn’t start.)

・My application is called from the shell scrypt I made for the test.(/etc/init.d/
・I set command “/etc/init.d/” to /etc/init.d/
・ includes other command like “touch /home/root/test.txt”

I prepared the application by the following steps:
・ Bulid the application with VM on windows PC
(VM:Orange - mangOH Dev using Legato 18.09.0 on Ubuntu 18.04)
・ Copy it to /home/root on WP8548 by SSH.
・ Grant an authority (666) to the application.

After the preparation above, I checked the application can be started by inputting the command “/home/root/[app name]” or /etc/init.d/ on legato.

Please guide me in this regards.