Add a derived table field as Group

[vincentc]

Hello,

I currently encounter a problem during the development of an ad hoc report.
I created a domain and in this domain, I use several tables with a derived table based on a simple SQL query (SELECT ... FROM ... WHERE). This query works and returns only 10 records.
A join is also shed on the derived table (I do not know if this important detail).
When I make my ad hoc report (format: table), if I add a field in my derived table as a column, it works perfectly. By cons, if I want to add it as a group (and that's what I want), I get the message"Loading ..." that appears indefinitely and nothing happens.
Does anyone know what can cause this?

In advance, thank you.

Vincent