my suggestion are going to sound like an IT suggestion (no offence), but i had a posting parked document problem too related to a lease back (doc type KR too). My solution: after several atempts i tried a simple thing… create a new document (delete the old parked document) and it worked fine after that.
I didn’t had error msgs like yours but instead i had several warning msgs (“enter a true account assignment object with revenues”) when i tried to post the parked document and in the end of all the warning msgs it didn’t posted.
But after i created a new document, and despite all the warning msgs i was able to post the document. Because… ?! Dont’t know why and my ABAP’s either.
Hope that helps…