Trouble making friends with TTrees

I have a TFile with a separate truth and reconstruction TTrees. I have tried to make one a friend of the other so that I can Draw with cuts on the other tree, but it doesn’t seem to be working.

[acas0001] run >> root ZTauTau_5188_lh_Tau1P3P.AAN.root
root [0]
Attaching file ZTauTau_5188_lh_Tau1P3P.AAN.root as _file0…
Warning in TClass::TClass: no dictionary for class AttributeListLayout is available
Warning in TClass::TClass: no dictionary for class pair<string,string> is available
root [1] OS0->AddFriend(“Truth0”)
(class TFriendElement*)0x948f5b8
root [2] OS0->Draw(“ComboMuTau_m”,“Truth0.Muon_N>0”)
TCanvas::MakeDefCanvas: created default TCanvas with name c1

This draws a blank canvas. But if I do OS0->Draw(“ComboMuTau_m”) or Truth0->Draw(“Muon_N”), then I gets plots with entries. I thought maybe nothing passed the cut, but if I logically flip the cut, OS0->Draw(“ComboMuTau_m”,“Truth0.Muon_N<=0”), I still get a blank canvas.


Most likely the problem is the same as the one described (and solved) at

In short, if this is an Atlas file, use the tree named ‘CollectionTree’.


Great. Thank you.