Can't zoom in TH1D - x-axis region

Hi, I’m a student in physics and I have some trouble with my code. It works but when I change the value of limInf and limSup, the data doesn’t zoom into the range that I want, it resizes itself.
I’m using


This pastebin(dot)com/KJAJgC5q is my entire code.

The two results:
graph_HV2000 copia.pdf (103.6 KB)
graph_HV2000.pdf (103.7 KB)

What I want is to zoom the region between 1200-1300 where I want to fit the max peak.

histoHV->GetXaxis()->SetRangeUser(limInf, limSup);
histoHV->SetAxisRange(limInf, limSup, "X");

Afterward, you may also need:
if (gPad) { gPad->Modified(); gPad->Update(); }