This is because there is no data to report off of. You need a table with a list of all of the tests that are available. Do you have access to create a view in the database? If so, I would create one that that does a "Select Distinct" of the tests from the employee test data. If not, you'll have to use a command for your report. How are your SQL skills?
The command will have something like the following logic:
Select the data that you're currently using on the report.
UNION ALL
Select the appropriate employee info, class name, and a null date
from the employee table and (
select the distinct test names for your date range - look at all records, not jut the specific employee records)
where the test name does not exist in the test table for this employee.
-Dell