I have done the following steps:
sudo add-apt-repository ppa:langdalepl/gvfs-mtp
sudo apt-get update
and updated some packages from update manager. After doing above steps I am able to see lumia phone name in file system. But when I try to mount device I am getting following errors:
Unable to mount RM-914|Nokia Lumia 520
Unable to open MTP device '[usb:001,010]'
Is there any way to solve these problem?