GetEntries() for new X range

Hello ROOTers.

I have a question.

I have a histogram. I have set new X range for my histo. And I call myhisto->GetEntries() for histogram with new X range. Because I want to know how many events are in new X range.

But I recieve number of entries for histo with old X range.

I have applied two pictures.
With old X range. And with new range.

Could you help me?