SFML not playing sound when run in background

Question

I wrote an image processing program(c++) which is working fine on my cubietruck, when I run the program in console everything is working fine and the sound plays as I desire(I use SFML libary) , I need my program run whenever linux boot on my cubie so I modify the rc.local file as bellow ::

alias ls="ls --color"

if [ -f /root/firstrun ]; then
    echo "first run setup"
    resize2fs /dev/nandb
    rm /root/firstrun
else
    echo "not first run"
fi
modprobe sunxi_coded
modprobe bcmdhd
ifconfig eth0 0 up
/root/shodet/shot
exit 0

when the linux boot, my program starts and is working, but there is no sound , so I open a console, killall shot and then start it again and then I have sound ! I have no idea whats wrong is it a SFML problem ? or something else I appreciate your help thanks in advance