Confused about assigning modifier keys

I'm just getting started with BTT and am a bit confused about how to properly use the modifier keys. I'm using a gaming keypad (Razer Tartarus Pro) for Photoshop work. I need to be able to push one of the keys assigned to Option (as well as shift) while I am doing things with the mouse or other keys on the main keyboard, do the action, then let go of the Option key on the Razer keypad and go back to normal work.

But it looks like when I assign the Option key to a key on the Razer (using the Modifier Keys) option in setting up a new trigger, I have the option of Option up or down. But if I select only one option in the trigger, the key "stays active" and I have to shut down BTT to gain access to the computer again. If I choose both up and down, hitting the key on the Razer doesn't seem to perform like it does on my normal keyboard.

What am I doing wrong?