Problem with plotted underflow bin in TH1D

Dear all,

I would like to make a plot with the following:

[li]data points (TH1D)[/li]
[li]error bands around the data (TGraphAsymmErrors)[/li]
[li]a few MC histograms (TH1D)[/li][/ul]

Something strange happens near the edges of my canvas: the MC histograms drop to zero. If I use GetXaxis()->SetRangeUser(xmin, xmax) to cut off these edges, the MC bins move.

In attachment you can find the plots with and without these adjusted axes. Could you please shed a light on this strange behaviour?

Plot_no_reduced_axis.C (59.4 KB)
Plot_no_reduced_axis.pdf (21.2 KB)
Plot_after_reduced_axis.C (58.7 KB)
Plot_after_reduced_axis.pdf (21 KB)

You are using a very old ROOT version 5.27/06b.
Try ROOT 5.34.