求救！！MulticastSocket UDP组播，joinGroup 错误

前段时间做UDP组播，加入路由器，来进行通信，一切正常。
现在手机开启便携式热点，进行通信就出现这个问题了，在  socket.joinGroup(group);  这段出现异常。

MulticastSocket socket = new MulticastSocket(12345);
    InetAddress group = InetAddress.getByName("224.0.1.1");
    socket.joinGroup(group);
     socket.setLoopbackMode(true);
     DatagramPacket packet;
       byte[] buf = new byte[256];
       packet = new DatagramPacket(buf, buf.length);
       DatagramPacket outPacket = new DatagramPacket(new byte[0] ,
         0 ,InetAddress.getByName("224.0.1.1") , 12345);

        //设置发送用的DatagramPacket里的字节数据
        byte[] bufff={1,2};
        outPacket.setData(bufff);
        socket.send(outPacket);// 发送
        boolean g=false;
        int tppp= socket.getTTL();
        socket.setTTL((byte)32);
        while(!g)
        {
         socket.receive(packet);
        if(bufff!=null)
         {

         }
        }
下面是 Log：
W/System.err(16100): java.net.SocketException: No such device
W/System.err(16100): at org.apache.harmony.luni.platform.OSNetworkSystem.setSocketOption(Native Method)
W/System.err(16100): at dalvik.system.BlockGuard$WrappedNetworkSystem.setSocketOption(BlockGuard.java:382)
W/System.err(16100): at org.apache.harmony.luni.net.PlainDatagramSocketImpl.setOption(PlainDatagramSocketImpl.java:198)
W/System.err(16100): at org.apache.harmony.luni.net.PlainDatagramSocketImpl.join(PlainDatagramSocketImpl.java:137)
W/System.err(16100): at java.net.MulticastSocket.joinGroup(MulticastSocket.java:190)
W/System.err(16100): at yhz.jzz.zzv.Listactivity.probe(Listactivity.java:104)
W/System.err(16100): at yhz.jz.zzv.Listactivity.onOptionsItemSelected(Listactivity.java:67)
W/System.err(16100): at android.app.Activity.onMenuItemSelected(Activity.java:2415)
W/System.err(16100): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:834)
W/System.err(16100): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:143)
W/System.err(16100): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:855)
W/System.err(16100): at com.android.internal.view.menu.IconMenuView.invokeItem(IconMenuView.java:601)
W/System.err(16100): at com.android.internal.view.menu.IconMenuItemView.performClick(IconMenuItemView.java:130)
W/System.err(16100): at android.view.View$PerformClick.run(View.java:9361)
W/System.err(16100): at android.os.Handler.handleCallback(Handler.java:587)
W/System.err(16100): at android.os.Handler.dispatchMessage(Handler.java:92)
W/System.err(16100): at android.os.Looper.loop(Looper.java:130)
W/System.err(16100): at android.app.ActivityThread.main(ActivityThread.java:3768)
W/System.err(16100): at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err(16100): at java.lang.reflect.Method.invoke(Method.java:507)
W/System.err(16100): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
W/System.err(16100): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
W/System.err(16100): at dalvik.system.NativeStart.main(Native Method)
--------------------编程问答-------------------- 自己顶一下。 --------------------编程问答-------------------- 发现个现象就是只有开启热点的手机本身出现这个情况，别的手机加进这个热点一切正常。
没人回复？？ --------------------编程问答-------------------- the same problem. Can you help me?

补充：移动开发 ,  Android