DAX issue

as I stated above, x-axis has 2 fields, 1st month and then 2rd region

my default dax is CALCULATE(COUNT('S rate'[success]),'S rate'[inclusion flag]="Y")/COUNT('S rate'[success])

so by default, the data will divide by month on 1st level & divide by region of 2nd level

and now my business have a requirement above this logic,

they want to see all regions available for every month

for. example, tho for nov month has data only for region apac, australia and la

they need to see other region as well with if numerator and denominator is not available (or blank) then it should show 100% or 1 and if numerator not available it should show 0 ( 0 by anything is 0)

this is the result I need to get

uae - 0

apac - 1

europe - 0.5

la - 0.5

afracia - 1

australia - 1

na - 1

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modified dax = CALCULATE(CALCULATE(COUNT('S rate'[success]),'S rate'[inclusion flag]="Y")/COUNT('S rate'[success]),CROSSFILTER(region[region],'S rate'[region],None))

this is the logic I wrote to get every region under a month, I got the regions with this logic but for every region I get same values as that month 

if I try ISBLANK(num) && ISBLANK(den),1 as one condition of switch statement which is my actual ask 

then I get 1 for the months that doesn't even have data, for example if my month columns has extra month like jan of 25, even if there is no data, i still will get 1 by logic

that will be wrong right?

this logic works when under my region drill down but for month it will show wrong values

both methods will show data as 0 for months which doesn't have date surrogate key in fact table