SUM quantity on a specific date

Im having a really hard time with a relaly basic measure but I cant figure out what Im doing wrong.

Ive got a quantity measure that sums a quantity column that works fine

I have a calendar table joined correctly to my sales table which works fine with any other measure and slicer

But Im trying to write a measure to just tell me the quantity for a specific date. Ive tried:

CALCULATE([Quantity], FILTER('Calendar', 'Calendar'[Date] = 07/07/2021))

and

CALCULATE([Quantity], FILTER('Calendar', 'Calendar'[Date] = DATE(07, 07, 2021) ) )
and

CALCULATE([Quantity], FILTER('Calendar', 'Calendar'[Date] >= 07/07/2021), FILTER('Calendar', 'Calendar'[Date] < 08/07/2021) )

and

CALCULATE([Quantity], FILTERS('Calendar'[Date]), 'Calendar'[Date] = 07/07/2021)

and

CALCULATE([Quantity], FILTERS('Calendar'[Date]), 'Calendar'[Date] >= 07/07/2021, 'Calendar'[Date] < 08/07/2021)

and

CALCULATE([Quantity], 'Calendar'[Date] = 07/07/2021)

Everything is returning me a blank value. Its such a simple measure but I cant figure out whats going on. Am I doing something wrong here?

Thanks for your help