as2 form not working within action scripts

this script is working on online but when i put this code within my project action scripts, its not working,,,

stop();

System.useCodepage = true;

send_btn.onRelease = function() {

    my_vars = new LoadVars();

    my_vars.sender = email_box.text;

    my_vars.subject = subject_box.text;

    my_vars.message = message_box.text;

    if (my_vars.sender != "" and my_vars.subject != "" and my_vars.message != "") {

        my_vars.sendAndLoad("mailer.php", my_vars, "POST");

        gotoAndStop(72);

    } else {

        error_clip.gotoAndPlay(72);

    }

    my_vars.onLoad = function() {

        gotoAndStop(73);

    };

};

email_box.onSetFocus = subject_box.onSetFocus=message_box.onSetFocus=function () {

    if (error_clip._currentframe != 1) {

        error_clip.gotoAndPlay(6);

    }

};