Jasper studio with datasource as XML not working on Sub reports

I have a XML from which I want to create a Jasper report keeping XML as datasource. Report contains a Sub report so I set tag in main report because I need to iterate through all but as root is now set as for Main report , i am unable to sent another tag which is not inside , to make things more clearer please see the XML bellow.

<Root>
  <containerInfo>...</containerInfo>
  <containerInfo>...</containerInfo>
  <containerInfo>...</containerInfo>
  <StuffingInfo>...</StuffingInfo>
  <StuffingInfo>...</StuffingInfo>
  <StuffingInfo>...</StuffingInfo>
  <StuffingInfo>...</StuffingInfo>
</root>

I need to set ContainerInfo as Root for main report and send StuffingInfo in "Data Source Expression" in sub report , which I can't do as Root is ContainerInfo and its not allowing Expression "../StuffingInfo" for subreports.

I have set Root node as ContainerInfo in main Report , so main report detail are working fine and I tried setting everything in "Data Source Expression" of sub report but nothing seems to work , data for sub report is coming all NULL.

Please let me know if my question is not clear enough. any help is most appreciated.