是因为新机型没在列表里的原因。
处理方法如下：
As far as I know, MTP works fine in Trusty. You can try this:
Uncomment #user_allow_other in /etc/fuse.conf.
Run lsusb and see your device‘s vendor ID. It will be something like 1d6b:0002. （执行lsusb命令，查找机器id，我的机器id是2a45:0c02）
Add the following line to /lib/udev/rules.d/69-libmtp.rules. （idVendor和idProduct的赋值记得改成你自己查到的结果）
ATTR{idVendor}=="1d6b", ATTR{idProduct}=="0002", SYMLINK+="libmtp-%k", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
Add the following line to /etc/udev/rules.d/51-android.rules. （同上）
ATTR{idVendor}=="1d6b", ATTR{idProduct}=="0002", MODE=”0666"
sudo service udev restart
sudo reboot
Replace the Vendor and Device IDs of course.
Like I said, MTP should work out of the box, but the above manually adds relevant entries to your devices list. （ubuntu14.04对MTP的支持是没问题的，只不过新机型没列出来）
魅蓝note2在ubuntu14.04下mtp模式无法自动mount的解决方法
原文：http://www.cnblogs.com/kkzxak47/p/4840608.html