No error bars visible for vertical TGraphErrors

ROOT
#1

hi everyone
I am trying to draw a TGraphErrors with a filled error band. I want the graph to be a vertical line so have the filled yellow error along the x direction. I am using the code below. However when I draw it I see the line but no error band. Why is this (when the line is horizontal and I set the PointError in y it works ok)?

cheers
Ellie

void TestRoot(){
  TGraphErrors *g_l2=new TGraphErrors();
  g_l2->SetLineColor(kBlack);
  g_l2->SetLineWidth(2);
  g_l2->SetFillColor(kYellow);
  g_l2->SetPoint(0, 0.1566, -0.05);
  g_l2->SetPoint(1, 0.1566, 0.1875);
  g_l2->SetPointError(0, 0.1, 0.0);
  g_l2->SetPointError(1, 0.1, 0.0);  
  g_l2->Draw("AL3");
  g_l2->Draw("LX");
}
#2

Your two points are aligned vertically and you have no error along Y… how can you expect to draw a band with that ?
See on the doc what the option 3 does …
root.cern.ch/root/html/TGraphPainter.html#GP03a

and try:

{
TGraphErrors *g_l2=new TGraphErrors();
g_l2->SetLineColor(kBlack);
g_l2->SetLineWidth(2);
g_l2->SetFillColor(kYellow);
g_l2->SetPoint(0, 0.1566, -0.05);
g_l2->SetPoint(1, 0.3566, 0.1875);
g_l2->SetPointError(0, 0.1, 0.1);
g_l2->SetPointError(1, 0.1, 0.1); 
g_l2->Draw("AL3");
g_l2->Draw("LX");
}