Aegisub help, HYDRA plugin

[ThePi7on]

Hi, I just added HYDRA script to Aegisub, and I want to create a vertical gradient, but I really can't figure out how to do it.
I read the guide, but it didn't help.



I selected "vertical" from the dropdown, but I don't know what to do next.

And obviously, if I click "apply" of "gradient", it gives this:


Do you guys know how to do it?