[Therion] bad scrap overlay

Hi, I am new therion user - hello everybody :-) I have a "bad scrap overlay" problem in a cave passage. The setting is very simple: two galleries (one scrap for each), with a junction at the ceilling. The lox file shows everything ok However, my plan pdf map shows the bottom gallery at the top (should be the opposite !). The problem remains with and without joining the scraps. I can't figure why. Could anybody help ? Have you got an idea of the possible reasons for bad scrap overlay ? thanks in advance Naomi