recording parameter changes in softsynth vst

Hi all,
I’m recording vst softsynths (such as ilosynth) in Cubase AI4. Everything is working well except that when I change parameters like filter resonance, cutoff, etc. while recording, the changes don’t get recorded. What am I missing? Is this even possible?

Sorry if this has been covered before, but forum search isn’t returning anything.

Do you have Write enabled on the VST’s GUI?

I did not. Turned it on, but didn’t see any difference. I then turned on Read as well, and it works! Thanks!