Sound error when exit game [iphone]

i’ve a strange error.

in my game, i turn off sound, and i save to database status of sound.
Then i kill process of game, and play again.
i turn on sound, but sound not play. i have to turn off and turn on again, sound play.

something wrong _

i check :

 bool music = CCUserDefault::sharedUserDefault()->getBoolForKey("music",true );

    bool sound = CCUserDefault::sharedUserDefault()->getBoolForKey("sound",true );



    CCUserDefault::sharedUserDefault()->setBoolForKey("music", music);

    CCUserDefault::sharedUserDefault()->setBoolForKey("sound", sound);


if(CCUserDefault::sharedUserDefault()->getBoolForKey("music"))

    {

       SoundManager::Instance()->playMusic();

    }

Thank u very muchhhh