What happens when you try both of the options from the note? In particular what happens when you actually fill the condition record tables? What is displayed in the condition record details of the created PO? I'm guess the condition records you manually pass in don't have any effect on the net price otherwise you wouldn't say it isn't working but do they show up in the condition record details as inactive?
The code you posted doesn't seem to have either of the suggestions from the note applied which makes it hard to know if there might have been some slip up while implementing those suggestions.