RooCmdArg ProjWData not working if passed indirectly

using namespace RooFit;

// PDF for arbitrary "time error" distribution

RooRealVar timeerror("timeerror","timeerror", 0.0, 1.0);

RooRealVar timeexp("timeexp","timeexp", \-0.3, 0.0, 1.0);

RooExponential exp("exp", "exp", timeerror, timeexp);

// proto data for time error

RooDataSet* proto = exp.generate(timeerror, 1000);

// PDF for abitrary "time" distribution depending on time errors

RooRealVar time("time","time", \-10.0, 10.0);

RooRealVar timemean("timemean","timemean", 0.0, \-10.0, 10.0);

RooGaussian gauss("gauss", "gauss", time, timemean, timeerror);

// dataset for time with correct time errors as proto data

RooDataSet* toydata = gauss.generate(time, 1000, ProtoData(*proto));

// fitting time distribution with time error as conditional observable

gauss.fitTo(*toydata, ConditionalObservables(timeerror));

// RooCmdArg for correct plotting (could be on stack, would not change anything)

RooCmdArg * arg = new RooCmdArg(ProjWData(timeerror, *toydata));

// Plot the distribution and PDF with above RooCmdArg fails (giving ProjWData directly works)

TCanvas c("c","c",800,600);

RooPlot* frame = time.frame();

toydata->plotOn(frame);

gauss.plotOn(frame, *arg/*,ProjWData(timeerror, *toydata)*/);

frame->Draw();

c.SaveAs("test.pdf");