Troubleshooting GPIOs (some can't be written)

I'm having some trouble getting my GPIOs to behave as I'd like. I don't know if my overlay is causing problems, or something else (it's here: http://pastebin.com/JqE4emX3). But right now, I can't use sysfs to write a value to a GPIO:

# echo 115 > /sys/class/gpio/export
# echo out > /sys/class/gpio/gpio115/direction
# cat /sys/class/gpio/gpio115/value
0
# echo on > /sys/class/gpio/gpio115/value
bash: echo: write error: Invalid argument

This is true regardless of whether or not I load my overlay. My base dtb looks like this: http://pastebin.com/Wja7ZQRk

This stuff used to work, so I may just be overlooking something, but I'm not 100% sure.

On Tue, 5 Apr 2016 18:46:21 -0700, Rick Mann
<rmann@latencyzero.com> declaimed the following:

I'm having some trouble getting my GPIOs to behave as I'd like. I don't know if my overlay is causing problems, or something else (it's here: http://pastebin.com/JqE4emX3). But right now, I can't use sysfs to write a value to a GPIO:

# echo 115 > /sys/class/gpio/export
# echo out > /sys/class/gpio/gpio115/direction
# cat /sys/class/gpio/gpio115/value
0
# echo on > /sys/class/gpio/gpio115/value

echo 1 > ...

  The values are numeric 0/1, not off/on

o.O

Sometimes I wonder why I even try to pretend to be an engineer of any kind. I knew that.

Thanks.