Block Tick Update Procedure not working

Should use blockticks, not entity ticks.

Its because on block tick doesnt provide an entity. Although you are searching for an entity in a cube of size 8. There actually is not event/target entity being provided by the trigger.

Instead of using the does entity of type player exist. Instead use entity iterator. Like so:

Then just repeat for your other values. You can either have them stacked or put them in the same if statements like you did in your original procedure. Idk which one will work better, but it depends on your geiger beep effect which I assume is a sound. So probably put them in if statements to be sure.

Actually for the procedure above you need a logic to check if entity iterator is the same as entity of type player/server player. Instead of the does entity exist at x y z block.