its been awhile since I had to do this but. here is what you will want to do. your problem is that it isn't passing the privs to allow you to read or write.
- open terminal
sudo apt-get install pmount udisks udisks2 gvfs consolekit
make a new file called 55-myconf.pkla
edit the file and input this
make a new file called 10-udisks.pkla
input this into the file
Now please make sure you are in the storage group, if you are not sure try:
do this as yourself not root
sudo usermod -a -G storage yourusername
Good luck hope this helps, like I said its been awhile since I had to do that.