Need help with formula

[Q]

What is wrong with:

Ability 2 Amount 2 Formula := iif([%Level%] > 3), (([%Level%] - 3) * 2), 0

SE V does not accept it and gives the error message of "incorrect number of parameters for function iif([%Level%] > 3)".

I want the Amount of Ability 2 (minesweeping) to be as follows:

Level 1 : 0
Level 2 : 0
Level 3 : 0
Level 4 : 2
Level 5 : 4
Level 6 : 6

Thank you for you help.