Other USB flashdrive will not mount

[walterbyrd]

FreeBSD 10.1. XFCE4.

I can mount it from the command line. When I am not running a DE, I just find out where it's mounted and do:

# mount_msdosfs /dev/da4s1 /mnt/drive

But when I am running XFCE4, and I plug in the thumb drive, I get.

Failed to mount media, and operation is already pending