环信demo运行出现Could not find class 'xxx', referenced from method xxx

Could not find class 'com.easemob.chatuidemo.ui.MainActivity', referenced from method com.easemob.chatuidemo.DemoHelper.onConnectionConflict
Could not find class 'com.easemob.chatuidemo.ui.MainActivity', referenced from method com.easemob.chatuidemo.DemoHelper.onCurrentAccountRemoved
Could not find class 'android.support.v4.app.af$d', referenced from method com.easemob.chat.EMNotifier.sendNotification
Could not find class 'android.support.v4.app.NotificationCompat$Builder', referenced from method com.easemob.easeui.model.EaseNotifier.sendNotification
Could not find class 'com.easemob.chatuidemo.ui.ChatActivity', referenced from method com.easemob.chatuidemo.DemoHelper$3.getLaunchIntent

求大神解决，很急，最近开发一个项目需要用到环信