Read from DSO rule type along with key figure summation

Hello all,

I want to read a key figure from a DSO in my transformation and sum it up if there are multiple keys in the lookup DSO. Is this possible with the Read from DSO rule type along with key figure aggregation type 'summation'? Currently what I'm seeing is that it is not adding up but reading only one line and displaying that in the target.

Thanks

Aadil