How to create a grouping with calculated Planned Hours

Hello

probably something basic for many of you :) I cannot seem to combine two things in grouping on the project level:

I would like to group tasks by name (it's a custom field and easily can be created as grouping) and display a SUM of Planned Hours for each person in the grouping line

Have a piece of code for the name:

textmode=true

group.0.linkedname=direct

group.0.namekey=Instructor's name

group.0.valuefield=Instructor's name

group.0.valueformat=customDataLabelsAsString

and a piece that i tried to integrate (obviously wrong..)

aggregator.function=SUM

aggregator.valuefield=workRequired

aggregator.namekey=workrequired

aggregator.displayformat=minutesAsHoursString

aggregator.valueformat=compound

It should look like on the screen shot (column Planned Hours), with a difference that I group by name not the planned completion date.

Could please anyone give me a hint how to do it?

Many thanks!

Marta