Ok just re-installed the mod, and I can now make it work as expected. The date format is the issue, because I was selecting the date format from the calendar, ie clicking the day of the month etc, it was inserting the date in the american format, the format is perfectly legitimate in the UK too, but it means different dates 04/08 is the 4th of August in the uk, but 8th of April in the US ... hence the problem.

The bias towards the American date is fine, but perhaps there should be something in place to warn, or suggest non-us dates should be entered manually, else it won't work. It will work if you are doing monthly reports but not if you are producing sales reports between two specific dates.

Thanks.