[B]Not sound in bootanimation at first boot[/B] topic

Not sound in bootanimation at first boot

Hello,

I have a Stock ROM deodexed by me, from firmware.
It works OK, but I have a problem that I do not know how to fix it.
At first boot, after install, I have not sound in bootanimation.
I saw that in /system/etc the power.ogg file is changed in power.ogg.backup
If I add another power.ogg in system/etc I have sound in bootanimation, and I have no more problems at next boots.
I made several attempts.
For example, after the first install i have added a flash bootanimation.
But after being loaded system, the file power.ogg becomes power.ogg.backup.
It is about a S5830 Stock ROM. It is my project.

How can I fix this?
Thank You.