How do I run a summon command based on the amount of HP the main mob has?

I have tried many lines of code, and none of them seem to work. This is the code I use to store the health score:

execute as @e[type=zombie,limit=1] at @s store result score @s Health run data get entity @s Health

This is the code I use to check if it’s equal to or under a certain amount and summon the mob:

execute if score @e[type=zombie,limit=1] Health matches ..20 run summon minecraft:wither_skeleton -106 80 -30

None of the command blocks work, and they don’t even have a log output. How do I run a summon command based on the amount of HP the main mob has?