Hi Divya,
If you suppress the section that holds the Subreport, then the shared variable will not contain any value.
Here's what you need to do:
1) Go inside the Subreport and suppress each section
2) In the Main Report, select the Subreport and reduce the size so that it appears no bigger than a 'dot'. You can then place this in some corner of the section and reduce the size of the section too.
-Abhilash