Week Number Ranges Multikey

[Andy H]

I have attached an extract from my database. I've successfully managed to implement a calculation field that calculates all the dates between the from and end date fields (courtesy of Andrew Persons, Excelisys from Brian Dunning's custom functions). Now I'd like to add a field which will calculate the week numbers which are between the from and end dates. I have managed this with some success by modifying the date range calculation. However, this calculation does not seem to work properly in all situations. In particular it does not work correctly when the from date field and end date are in different years. The date range calculation works flawlessly, but the week range does no function in this instance. Does anyone have experience of implementing such a calculation or can anyone help with correctly modifying this calculation?

WeekNoRanges.zip