Pen Refuses to Work

[Fαℓℓιиg Uρ]

Hello!

As you can tell from the subject, my Huion H160Pro pen is refusing to work. I charged it (the light is off, so it's fully charged) and it suddenly stopped allowing me to use it?

When I place the pen down on the tablet, the tablet acknowledges it's presence, with the small light glowing green every time I touch it to the surface. But when I look on my screen, (I use sai, and it has worked with it before??) not even it's little cursor has moved. Not a single mark on the canvas.

What happened?? (Again, it worked perfectly fine before.)