Y-axis range is not changed

Newbie
1

Hi,
The range of y-axis is not changed.
I want to set it only upto 3000.
All the necessary files are updated below:
basic.root (30.1 KB) trio.C (3.2 KB)

Have a nice day.

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

2 
// ...
diff->Add(h2,-1.0);
diff->SetMaximum(3000.);//along Y
// ...