为什么按钮单击事件不起作用？

var chatMessages = [{
  name: "ms1",
  msg: "1 этап <div class='box'><button class='btn'>next</button></div>",
  delay: 600,
  align: "left",
  
},
{
  name: "ms2",
  msg: "успешно. далее!",
  delay: 600,
  align: "right",

},
{
  name: "ms3",
  msg: "Второй этап <div class='box'><button class='btn'>next</button></div>",
  delay: 600,
  align: "left",
 
},
{
  name: "ms4",
  msg: "Успешно",
  delay: 600,
  align: "right",
 
},
{
  name: "ms5",
  msg: "Третий этап <div class='box'><button class='btn'>next</button></div>",
  delay: 600,
  align: "left",
  
},
{
  name: "ms6",
  msg: "Конец.",
  delay: 600,
  align: "right",
  
}
                   ];
var chatDelay = 0;

$(document).on('click', '.btn', function(){
  console.log(111);
  $(this).parent('.box').toggleClass('active');
});
function onRowAdded() {
  $('.chat-container').animate({
    scrollTop: $('.chat-container').prop('scrollHeight')
  });
};
$.each(chatMessages, function(index, obj) {
  chatDelay = chatDelay + 1;
  chatDelay2 = chatDelay + obj.delay;
  chatDelay3 = chatDelay2 + 10;
  scrollDelay = chatDelay;
  chatTimeString = " ";
  msgname = "." + obj.name;
  msginner = ".messageinner-" + obj.name;
  spinner = ".sp-" + obj.name;
  if (obj.showTime == true) {
    chatTimeString = "<span class='message-time'>" + obj.time + "</span>";
  }
  $(".chat-message-list").append("<li class='message-" + obj.align + " " + obj.name + "' hidden><div class='sp-" + obj.name + "'><span class='spinme-" + obj.align + "'><div class='spinner'><div class='bounce1'></div><div class='bounce2'></div><div class='bounce3'></div></div></span></div><div class='messageinner-" + obj.name + "' hidden><span class='message-text'>" + obj.msg + "</span>" + chatTimeString + "</div></li>");
  $(msgname).delay(chatDelay).fadeIn();
  $(spinner).delay(chatDelay2).hide(1);
  $(msginner).delay(chatDelay3).fadeIn();
  setTimeout(onRowAdded, chatDelay);
  setTimeout(onRowAdded, chatDelay3);
  chatDelay = chatDelay3;
});

#wrapper {
  width: 600px;
  margin: 50px auto;
}

body {
  font-family: Arial;
  background: #fff;
}

.chat ul {
  margin: 0px;
  padding: 0px;
  list-style: none;
}

.message-left .message-time {
  display: block;
  font-size: 12px;
  text-align: left;
  padding-left: 30px;
  padding-top: 4px;
  color: #ccc;
  font-family: Courier;
}

.message-right .message-time {
  display: block;
  font-size: 12px;
  text-align: right;
  padding-right: 20px;
  padding-top: 4px;
  color: #ccc;
  font-family: Courier;
}

.message-left {
  text-align: left;
  margin-bottom: 16px;
}

.message-left .message-text {
  max-width: 80%;
  display: inline-block;
  background: #fff;
  padding: 15px;
  font-size: 14px;
  color: #999;
  border-radius: 30px;
  font-weight: 100;
  line-height: 1.5em;
}

.message-right {
  text-align: right;
  margin-bottom: 16px;
}

.message-right .message-text {
  line-height: 1.5em;
  display: inline-block;
  background: #5ca6fa;
  padding: 15px;
  font-size: 14px;
  color: #fff;
  border-radius: 30px;
  line-height: 1.5em;
  font-weight: 100;
  text-align: left;
}

.chat {
  border-radius: 30px;
  padding: 20px;
  background: #f5f7fa;
}

.chat-container {
  height: 400px;
  overflow-y: scroll;
  padding-right: 16px;
}

.spinme-right {
  display: inline-block;
  padding: 15px 20px;
  font-size: 14px;
  border-radius: 30px;
  line-height: 1.25em;
  font-weight: 100;
  opacity: 0.2;
}

.spinme-left {
  display: inline-block;
  padding: 15px 20px;
  font-size: 14px;
  color: #ccc;
  border-radius: 30px;
  line-height: 1.25em;
  font-weight: 100;
  opacity: 0.2;
}

.spinner {
  margin: 0;
  width: 30px;
  text-align: center;
}

.spinner > div {
  width: 10px;
  height: 10px;
  border-radius: 100%;
  display: inline-block;
  -webkit-animation: sk-bouncedelay 1.4s infinite ease-in-out both;
  animation: sk-bouncedelay 1.4s infinite ease-in-out both;
  background: rgba(0,0,0,1);
}
 
.spinner .bounce1 {
  -webkit-animation-delay: -0.32s;
  animation-delay: -0.32s;
}

.spinner .bounce2 {
  -webkit-animation-delay: -0.16s;
  animation-delay: -0.16s;
}

@-webkit-keyframes sk-bouncedelay {
  0%,
  80%,
  100% {
    -webkit-transform: scale(0)
  }
  40% {
    -webkit-transform: scale(1.0)
  }
}

@keyframes sk-bouncedelay {
  0%,
  80%,
  100% {
    -webkit-transform: scale(0);
    transform: scale(0);
  }
  40% {
    -webkit-transform: scale(1.0);
    transform: scale(1.0);
  }
}

<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script>
<div id="wrapper">
  <div class="chat">
    <div class="chat-container">
      <div class="chat-listcontainer">

        <ul class="chat-message-list">
        </ul>

      </div>
    </div>
  </div>
</div>