If the subreport is located in the Details section of the report:
  1. Move Subreport out of Details into Report Header or Report Footer section
  2. Preview the report

If the subreport is located within the Group Header section of  the report with multiple groups:

Move the subreport into the Report Footer section of the main report if possible, or follow the steps below -
  1. Right click on the subreport
  2. Select Change Subreport Links
  3. Add the fields used to create all the groupings in the main report
  4. Open the subreport (double-click the subreport from the main report)
  5. Click on the Select Expert icon (hand with two circles)
  6. Ensure that the group field names are equal to the parameter (ex: {GROUPNAME1.EN_US} = {?Pm-groupname1} )
  7. Click OK