✅ The event can only appear on the left hand side of += or -=

Hello there, so I'm trying to change the getter/setter (adder/remover?) of my events. The events commented out is how they were originally and had no errors. When I changed the events to how they appear in the first image I'm getting the errors you see in my second image and I'm not sure why.
Thanks for the help.
Edit: These are both in the same class if that matters