RooMCStudy and ConditionalObservables

I’m having some problems with RooMCStudy and ConditionalObservables. I’m also building my pdf using RooSimPdfBuilder, so that might be related to the problem.

I’m getting the error:

[#0] ERROR:InputArguments – RooMCStudy::RooMCStudy(simPdf) ERROR: unrecognized command: ProjectedObservables

Below are the relevant portions of my code (in pyROOT). mctDist is a pdf I wrote in using one of the factory classes.

mctPdf = mctDist("mctPdf","mctPdf", mct, smct, ep, weight, effslope)

# categories
decayType = RooCategory("decayType", "Decay Type")

builder = RooSimPdfBuilder(RooArgSet(mctPdf))
config = builder.createProtoBuildConfig()
config["physModels"] = "mctPdf"
config["splitCats"] = "decayType"
config["mctPdf"] = "decayType : effslope"

mcstudy = RooMCStudy(pdf, RooArgSet(), RooFit.ConditionalObservables(RooArgSet(smct)), RooFit.ProtoData(mc, True))

Any idea what’s going on here? I never use ProjectedObservables, so presumably it gets called internally somewhere. I found this thread: RooFit problems where it looks like the poster is seeing a similar error.