TFraction weird fit

Hello everybody,

I have a big and weird problem with TFractionFitter.
I have some mc histograms and a data one. I want to fit them in a small ROI (see the code), and each times, independently with the constraints, the factors go to their low limit.
When I want to see something like data->Draw(); fit->GetPlot()->Draw(“same”), I seems that getplot gives the sum mcs + data, something like that.

I have joined the code and an example of histograms which reproduce the problem. I need help !!

Thank you
testmc.root (8.87 KB)
tffit.C (880 Bytes)

I found the origin of my problem,
I realized that the fit factor are not direct factor of the mc histo, but with a normalization based on the data. It’s my bad, but I think that it should be explicitly explained in the documentation.