i would like to explain something.
first of all, %region at player% is not a thing, it's %player's region% and another thing, you can't tell skript to do nothing, you need to set something. so if you want to tell it to do nothing, you'd simply add "stop".
also, using "" doesn't work like that. if you wanna use quotes then you're saying that this is custom. %block under player% shouldn't be a thing, it should be

Code (Text):

1. if block under player:

same goes for the iron block.
I would usually give people the full code, but I'm tryna help people. I feel like in this situation, helping would be explaining to you without giving the full solution to make you a better coder.

 

Many things here.

- Its %player's region
- instead of cancel event here, you'd use stop.
- %block under player% doesn't exist! Try doing

Code (Text):

1. if block under player:

- There are many instances where you are trying to end the code without doing anything. Again, try stop.

When Skripting, try looking over the documentations. There are a few out there which would help, so I'll list a few for you!

- https://skriptlang.github.io/Skript/index.html
- https://en.njol.ch/projects/skript/doc
- https://docs.skunity.com/syntax/