Backup using adb on a phone with a dead screen

I have a Galaxy S3, screen is visually and touch impaired. It is USB debug enabled, un-rooted.

I'm able to use Droid@Screen to see my screen, which i'm able to unlock. I then run this command:

adb backup –apk –shared –all –f /backup/mybackup.ab

Which then initiates a backup on the phone. On the screen I can see it asking for an encryption password, which i provide by keyevent through adb. The final sticking point, is being unable to find a keyevent which will press the "Backup up my data" button. I am able to tab to it, and have it highlighted, but the 'space' and 'enter' events do not trigger it, as well as 'soft_right'.

I'm getting my keyevents from HERE.

If there is another way for me to dump the ab, that would be awesome.