TEfficiency has weird error bar when use weight

Hello Rooters,
I use the TEfficiency to draw the efficiency of histogram with weight. Here is what I did:

  • Declare the TEfficiency object, something like:
    Eff_Total = new TEfficiency(“Eff_Total”, “Total”, 50, 0., 250.);

In the event loop, I filled the TEfficiency object as the following:
Eff_Total->FillWeighted(LevelPassed, EvtWeight, x);

When I draw the histogram, It shows something like this: (in the attachment)
Do you know what is the problem with the errorbar in high efficiency region? I don’t suppose that it could be that bad. I use the ROOT version 5.32.00_64