I wanted to add two different TGraphs (Corresponding to two calorimeters) into
the same pad.
So in the xml file I did:
<Graph>
  <GraphName>MyGraph</GraphName>
  <GraphFolderName>mygraphs</GraphFolderName>
  <GraphType>TGraph</GraphType>
<GraphArraySize>2</GraphArraySize>
  <GraphXLabel>Event no.</GraphXLabel>
  <GraphYLabel>Island no.</GraphYLabel>
  <GraphXmin>0</GraphXmin>
  <GraphXmax>10000</GraphXmax>
  <GraphYmin>0</GraphYmin>
  <GraphYmax>100000</GraphYmax>
 <Argus>
<Tab>
      <TabName>SummaryFCBank</TabName>
    <ObjectArrayIndex>0-1</ObjectArrayIndex>
      <Index>1</Index>
 <DrawSamePad>true</DrawSamePad>
    </Tab>
  </Argus>
</Graph>


And in src/tasks:
in the HGUITFillHisto.cpp code I did:
 for(int icalo=1; icalo<3; icalo++)   [For each calorimeter there is one bank, and one n_islands value from that
bank per event.]                        
    {
GetMyGraphAt(icalo-1)->SetPoint(gAnalyzer->GetCurrentEventNumber(),gAnalyzer->GetCurrentEventNumber(),n_islands);

 GetMyGraphAt(0)->SetMarkerColor(2); 

 GetMyGraphAt(1)->SetMarkerColor(3);

 ArgusHistoDisplay::SetLimits(GetMyGraphAt(icalo-1));

}

But then I get an empty pad in the tab. 
It works when I create the TGraph for only one calorimeter, using GetMyGraph().

Any help would be much appreciated.

Thanks!
Sudeshna