isNil help in script

trying to get this to work but im not 100% what ive done wrong.

if (isNil("commonsense"))then{
commonsense = 0;
};

I'm trying to assign a value of 0 to commonsense if it has no value assigned.
Tried running this in Arma 3 to test it in my full script but to no avail.
Any pointers on my error would be good, as im certain that this is a knowledge gap

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Solved, was a syntax error.