[mythtv-users] External drive for recordings

[MS]

Folks:

I have been unable to persuade Myth to record to an external USB hard 
disc.  For instance -

/media/gt/HD2012/mythtv/recordings = 775 mythtv:mythtv

Set this in the Back End Default Directories and it is ignored even 
though mounted and accessible by other means.

I have succeeded previously so I must be missing something basic.

Myth 1.026 under Ubuntu 13.04 running on a Revo.

Any thoughts?  Many thanks.

GT