Problem with classification in PP order types

Hi!

I have a problem with PP order types and classification. I checked the classification in PP order types, and couldn't create PP orders (was given an error message). I had to go to OKQ3 (define reference characteristics) and generate some characteristics (don't know if i chose good ones) and after that go to OKKC (selection screen for requested selection) and finally to OKTO (change view Summarization Hierarchy).

I did some settings there - so now PP orders can be created but I don't know what the most common standard settings should be to have good report basing on them.

Hope sb can advise me on that.