How do i create Count() aggregation

[JiriPrajz (Prajz Jiří)]

I have relationship master detail.

I want to create an aggregation count field . The field count child row for each parent row.

I made this:

Then i added the field into screenSection.

But after show screen i got this:

I want show on screen master detail .

[JiriPrajz (Prajz Jiří)]

Solution is change Counting over Id to different field (ie: RecordCreated).

And Result: