problem Scale_Expression controller

In maxscript user's gude is method for Scale_Expression controller.

--Methods:

--<boolean>AddScalarConstant<&TSTR>Name <float>Constant

--Name is In parameter

--Adds a scalar constant. The first argument is the name of the --scalar. The second argument is the constant value to be --assigned to the scalar.

--I write some script

se=Scale_expression.AddScalarConstant "RER" 50.0

$.scale.controller=se

  --and got

-- Argument count error: AddScalarConstant wanted 3, got 2

--What happend????????