dielectric_LUTDAVIS

hello,everyone. I have a question, I would like to ask you to help me. A LYSO wraped by teflon.
G4OpticalSurface* OpRefCrySurface1 =new G4OpticalSurface(“LYSO-teflon-Surface”);
OpRefCrySurface1->SetType(dielectric_LUTDAVIS);
OpRefCrySurface1->SetModel(DAVIS);
OpRefCrySurface1->SetFinish(PolishedTeflon_LUT);

I find light collection efficiency is same when setFinish is PolishedTeflon_LUT or PolishedESR_LUT.
Is this normal?
And When I set the Boundary Process is dieltectric_dieltectric、 UNIFIED、groundbackpainted、SigmaAlpha=0.1.The light collection efficiency is 20%.But when I do not use reflector, the light collection efficiency is 33%.
Thanks.