From within Cognos Report Studio
1) Option A: Count(Rows for the report)
2) Option B:
Associate the Page object with the Query that serves the page, and then create a Query Calculation, not a Layout Calculation, that uses two key functions -- Count, for.
ie. count([Product Line] for report)
3) Additional Tips when there's no results at all:
You should create a Layout Calculation with the following expression:
IF ( [Query1].[Product Line Count] > 0 )
THEN ( [Query1].[Product Line Count] )
ELSE ( 0 )
