Exploding barrels don't work, why not?

In my game, when you shoot a barrel, there will be an explosion and small bricks will splatter around, then the barrel will explode, however, it's not working. What am I doing wrong in the script? Do I need a special function for hit or something?

function onTouched(hit)
	if hit.Name == "Bullet" then
		local explosion = Instance.new("Explosion", script.Parent)
		local maxDamage = 50
		explosion.BlastPressure = 0
		explosion.BlastRadius = 8
		explosion.Hit:connect(function(hitPart, partDistance)
    		local humanoid = hitPart.Parent:FindFirstChild("Humanoid")
    		if humanoid then
        		local distance_factor = partDistance/explosion.BlastRadius
        		distance_factor = 1 - distance_factor
        		humanoid:TakeDamage(maxDamage*distance_factor)
    		end
		end)
		for i = 1,8 do
			local debris = Instance.new("Part", game.Workspace)
			debris.FormFactor = "custom"
			debris.BrickColor = BrickColor.new("Black")
			debris.Size = Vector3.new(0.6, 0.6, 0.6)
		end
		script.Parent:Destroy()
	end
end
 
script.Parent.Touched:connect(onTouched)

Line 17 -- > "Custom"