I'm having a difficult time figuring out why my pen pressure isn't working anymore?

When I first downloaded the exe it was working perfectly, but suddenly i joined my friends room and it wasn't an option anymore? how do i fix this? All it does now is glitch and doesn't give me the pen pressure option, just the size. My tablet is plugged in and everything, it works perfectly fine on SAI. I don't know what I did to make it change??