Solved Block has problems

[Dxn]

on projectile hit:
  projectile is an snowball:
    play sound "expl.bazooka" with volume 100 with pitch 1 at shooter for shooter
  create an explosion of force 1
  loop blocks in radius 6 around event-location:
    add 1 to {explosiondurability::%loop-block%}
    if loop-block is oak wooden plank:
      {explosiondurability::%loop-block%} is more than or equal to 4
      set loop-block to air
    if loop-block is cobblestone:
      {explosiondurability::%loop-block%} is more than or equal to 5
      set loop-block to air
    if loop-block is spruce wooden plank:
      {explosiondurability::%loop-block%} is more than or equal to 6
      set loop-block to air
    if loop-block is obsidian:
      {explosiondurability::%loop-block%} is more than or equal to 7
      set loop-block to air

I have a problem. If you build as example some cobblestone somewhere and the blocks get destroyed by the snowball, if you place the blocks again they will instantly blow instead of getting destroyed by using the snowball 5 times. Like "{explosiondurability::%loop-block%} is more than or equal to 5" you gotta use the snowball 5 times to destroy the blocks, but they get destroyed instantly. Please someone help me!

 

[Nikd0]

I believe you have to delete this value=variable when the blocks are removed.

set loop-block to air
clear {explosiondurability::%loop-block%}

Also, it should be probably cleared when you remove it by yourself too:

on break:
  {explosiondurability::%event-block%} is set
  clear {explosiondurability::%event-block%}