I'm trying to model SPX with SPY so I want to reduce the commissions to 1/10 of normal. Can someone help me with the constant fee model on options?  I can't get it to work. I have tried:

Securities[spySymbol].FeeModel = new ConstantFeeModel(.06M);


option.FeeModel = new ConstantFeeModel(.06M);

Both have same results which is $.50 per a contract, the default behavior.