Scenario:
When I pull a Extension details report for a set period, I have a result.
When I pull Department Summary by Extension for the same period, I have no result.
If I pull Extension details report for the same period and select a department, I have no result.
Try the following:
Blank the extension and department file and add only one extension, for more details see:
How do I import extensions from a file into TNG?
Now pull the report and select only the department added.
If you now have a result, you need to add all your extension names again (see above link for steps).
Once all extensions imported, you need to disable the import extensions option, to view the report.
If you stil have no result, you need to do a synchronize data, see forum post:
How do I synchronize TNG data?