HT1338: OS X: Updating OS X and Mac App Store appsLearn about OS X: Updating OS X and Mac App Store apps
Currently Being ModeratedDec 11, 2012 2:31 AM (in response to iain186)
Do you see anything else in the Time Machine message?
Currently Being ModeratedDec 11, 2012 3:22 AM (in response to iain186)
Can you see your WD Passport in finder?
Currently Being ModeratedDec 11, 2012 3:41 AM (in response to iain186)
How to back up my imac to a WD my passport 1tb.?
I keep getting "Timemachine cannot back up message
That's a portable port powered drive and not advised to be used as a TimeMachine backup.
Use a self powered drive instead.
Use the port powered drive for portable storage like it was intended.
Apple is now cutting off the power to some port powered drives because they are drawing too much current and killing people's batteries on laptops.
Also read here for diversifing your backups, with TimeMachine people make mistakes in judgement about it and lose their data.