Column group

Hi all,

I want to create a report grouping by column but when I try to do it I get this output:

Bunitname1 Bunitname2
Tenant1
Tenant2
                      Tenant3
                      Tenant4

When I would like to obtain:

Bunitname1| Bunitname2
Tenant1   ..... Tenant3
Tenant2   .....  Tenant4

I found an answer speaking about matrix and including one matrix inside another but is not working it display only one row probably I am doing something wrong. There is any other way to obtain this result?

Thanks

Federico