…interesting…took me a while to figure this out:
I tried to create a minimal example and wasn’t able to reproduce the error, now I got it.
I’m drawing the histro and graph inside a Loop()-method, which was initially created by TTree::MakeClass.
Seems that some directories and paths are bent when using these constructions - I had a similar issue in the past (see here: Histograms not drawn inside Looper-Class)
indeed
gROOT->cd();
before histocreation solves the issue.
Same applies to
h->SetDirectory(NULL);
after histocreation.
I was wondering why
TFile *outfile = new TFile("out.root","RECREATE");
TDirectory *dir = outfile;
dir->cd();
before the histocreation is not working
Georg