Issue loading ROOT spectrum files in HDTV

[janmayer]

I found this in my mails, maybe something for the docs?

Dear Sir,

I hope this message finds you well.

I am currently using HDTV (Python 3.8, ROOT 6.32.06) for nuclear spectrum analysis. I have been trying to load a simple 1-D ROOT histogram file created both in C++/ROOT and in PyROOT, but HDTV consistently reports:

TH1::TH1:0: RuntimeWarning: nbins is <=0 - set to nbins = 1
ERROR: Failed to get data from file
WARNING: Could not load .root'None

The same .root files open correctly in ROOT (rootls, TBrowser, etc.), so the files themselves seem valid.
Could you please advise what exact ROOT file structure or object type HDTV expects for reading 1-D spectra?
If there is a preferred naming convention (e.g. directory name, histogram class, or serialization format), I would be grateful for some guidance.

Thank you very much for your time and for maintaining such a useful tool.

With best regards,
redacted
Variable Energy Cyclotron Centre, Kolkata