Extractor for purchasing of external services

Hi forum,

I need to extract the following key figures for purchasing of External Services:

- PO value / quantity

- Accepted value / quantity

- Invoiced value / quantity

These KFs should be reported by Service Nr., Purchasing Group and Purchasing document

The standard BI Datasource for External Services 2LIS_02_S174 does not cover my requirement, because it does not include Purchasing Group, Purchasing document.

Now I am trying to build my own extractor and would like to know from which tables I can extract the data and how. The Infostructure S174 is not what I need, because it does not contain all characteristics I need.

I am thinking of using tables ESLL (Service line items), EKPO (Purchase order line items) and EKBE (Purchase order history). But I don't how to connect all the needed information.

Can anybody help?

Thanks in advance,

Alex