This works well.

Code:
function FeToJulian(DD_MM_YYYY)
	rD = String.Left(DD_MM_YYYY, 2); rM = String.Mid(DD_MM_YYYY, 3, 2); rY = String.Right(DD_MM_YYYY, 4);
	rDate = os.time({day=rD, month=rM, year=rY });
	return Math.Floor((rDate / 86400) + 2440588);
end
...