Need help setting Z = 0 in Kelant C50 Mono

Hi all,I need some help setting Z=0 in my Kelant C60 Mono. I have leveled the bed with paper, and now I am trying to set the current position as Z=0. Please bear in mind that this is my first resin print try out ever.The issue is that when I tap the option "Set Z=0", it instructs me to "Home first, then move Z to the bottom." (attachment), even though I have already been doing this. As per the message, I understand that the current position is not set as Z=0, and I can't figure out how to make this work. What could I be missing here? Is my understanding about "Set Z=0" correct, i.e., "take the current Z position and never go below it."?Thanks in advance!

Resolved. If you are a beginner in resin 3D printing, make sure to *remove*, not loosen, the bed levelling screws before levelling and *homing*.