Assigning Substances to a Report 
Prerequisites
The report may not have status RR (report request), GP (generation possible), SE (system error), or GF (generation failed).
You must have authorization to process the report header.
Procedure
See:
Processing Worklists for ReportsIf the R/3 System finds one or more reports that correspond to your search criteria, the Report Management: Report Tree screen appears.
The report header data are displayed.

You can only assign substances for which no released reports for the same generation variant exist.
See also:
Substance Assignment