Subsequent datasets not normalized to 1st dataset in rooplot


I’m trying to plot multiple datasets in the same rooplot. To my knowledge, all subsequent datasets added to the rooplot are normalized to the 1st added dataset. However, the 2nd dataset is obviously not normalized to my 1st. Does anyone know why this might be? Here are my instructions for plotting

  RooBinning b = RooBinning(80,0,mtmax); // 2.5 GeV per bin
  dataSet->plotOn(frameMt, RefreshNorm(), Binning(b), DrawOption("p"),

mcWSet->plotOn(frameMt,Binning(b), LineColor(kBlack), FillColor(0), DrawOption("f"));