simple study trigger through think or script using ParabolaSars

[sf8193]

input accelerationFactor = 0.02;
input accelerationLimit = 0.2;

def sar = ParabolicSAR(accelerationFactor=accelerationFactor, accelerationLimit=accelerationLimit);

I get a "No such function: ParabolicSAR at 7:11". Can anyone point me to why this doesn't work here but works elsewhere?