is this just for display or do you then need to do something else with that information?
for just display purposes (assuming you want the maximum date per grouplevel 2) there are a few ways.
1. do an insert summary of the datefield at group level 2. Leave the summary in group footer 2 and hide all your details.
2. do an insert summary of the datefield at group level 2. Go into the section expert, select the detail section, click on the 'suppress no drill down' formula box (x-2). enter you suppress criteria here.
NOT({urslabs.testdate} = Maximum ({urslabs.testdate},{group field needed here})
3. sort on test date ascending. place the date field in teh group footer and suppress all detail.