A small problem and solution for Flash built-in class sound

Solve | problem: Two voices cannot be controlled independently
var _tmp;
var s1_sound = new sound ();
var s2_sound = new sound ();
S1_sound.attachsound ("S1");
S2_sound.attachsound ("S2");
S1_sound.start (0,1000);
_btn.onpress = function () {
_tmp =!_tmp;
if (_tmp) {
S2_sound.start ();
} else {
S2_sound.stop ();
}
This code wants the sound in the library to S1 as a background music, while S2 is controlled by the button _btn (click play/click to stop).
--but it backfired. Here's a s2_sound.stop () not only the s2_sound stopped, but also the S1_sound also stopped.
Workaround: The sound is loaded by an external. mp3 file.
var _tmp;
var s1_sound = new sound ();
var s2_sound = new sound ();
S1_sound.onload = function () {
This.start ();
}
S1_sound.loadsound ("S1.mp3");
S2_sound.loadsound ("S2.mp3");
_btn.onpress = function () {
_tmp =!_tmp;
if (_tmp) {
S2_sound.start ();
} else {
S2_sound.stop ();
}
The control section (_BTN) code has not changed and the problem has been resolved.