Using CSAP for archaeoastronomy I found that equinoctial sunrises for 2500 BC occurred in two quite different places. Starry Night Support have suggested a number of reasons citing among other things the effect of precession and the change to the Gregorian calendar. I have explained in reply why none of the suggested causes could possibly be correct. It appears however that they think the matter is resolved. Very frustrating - and it naturally produces doubts as to the accuracy of other features of the programme.