EMS dynamic solar transmittance

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Hi I am trying to simulation a window which has dynamic Solar Transmittance. I prepared the following code for that. It does not work. Could you please help me fixing that?

EnergyManagementSystem:Sensor,
  T1,
  Environment,
  Site Direct Solar Radiation Rate per Area;

EnergyManagementSystem:Actuator,
  T,
  b_0_Srf_2_glz_0,
  WindowMaterial:Glazing,
  Solar Transmittance at Normal Incidence;

EnergyManagementSystem:Program,
  D,
  SET Site Direct Solar Radiation Rate per Area = T1,
  if site Direct Solar Radiation Rate per Area >= 300,
  Solar Transmittance at Normal Incidence = 0.2,
  ELSEIF site Direct Solar Radiation Rate per Area < 300,
  Solar Transmittance at Normal Incidence = 0.5,
  ENDIF;

EnergyManagementSystem:OutputVariable,
  M,
  M-b-0,
  Averaged,
  SystemTimestep;

Thanks