Subreport does not show

I have a main report bound to a table. I have a subreport which contains only
DCOUNT controls of account numbers associated with specific groups from the
main table.

I can see the subreport alone in design or print view displaying all the
info but I cannot see the subreport in Print view in the main table.

I have tried changing the Master/Child fields to the account numbers then
the groups. I have moved the subreport name from the Report Header section to
the Page Header section. I created the subreport first and dragged it onto
the main report.

Obviously I am doing something wrong, but what is it? I have many subreports
which are ready to be added to the main report, all of the same style.

Thanks in advance.