How does the spell damage work (mathmaticaly)

[cuelakits]

I am making a map with low stats. like the first level of units have 10 health and 1 attack, now im trying to make hero abilities that do low damage, and when i put the data in, it wont do the damage i tell it to. Take Breath of fire for example the data. For the first level of the spell the data is "Level 1 - Data - Damage: 1 , Level 1 - Data - Max Damage: 3" and it does 0 damage (checked if armor has anything to do /w it, and it shouldnt reduce any damage) , then the next level "Level 2 - Data - Damage: 3 , Level 2 - Data - Max Damage: 5" it does 1 damage. is there a mathematical formula behind this im not catching? how does it work? sorry if i sound like a noob