Hi Angelos,
Your first issue it was for
"Finite scheduling indeed worked but production levels did not work correctly. I had many cases where production orders of next level started before production order of previous level finished.
What would you suggest me to do?"
Are you OK with this?
If you have implemented the note, you have to run the heuristic SAP_PP_009 with the option Find slot just one time. Is not necessary to have two steps. Normally the heuristic will explode the BOM and do a finite capacity planning in one shot.
Also, check your work center to see if Finite Capacity option is selected.
I don't understand what are you trying to do with running the "Heuristic without Finite Scheduling strategy". Is this the heuristic SAP_PP_009 with Infinite Planning strategy as selection? If yes, is normal to have over capacity.
Thanks.
Regards, Marius