Business days should not change

[Avivek]

I created a business days which is the distinct count of days of the date column.  I had created measure for Avg Sales and my measure is total sales/business days, but for this division the avg sales is calculated as total sales/7 instead of total sales/11.

How can we make sure that the avg sales for all the divisions are calculated based on total business days irrespective of how many business days is for different divisions.