Total sales is 100% Calculation

Hi, i have tried solving this calc for the whole day but to no avail.

Sincerely looking for help to calculate % of Sales in beast mode. I need my sales (of the selection whether by calendar type, location, custom period) to be always 100%, the sum of each category (numerator) will be divide by the total sales (14m in this case as denominator) to get the % of sales.

This is my current formula but it doesn't work as intended

SUM(Actual Custom) /
NULLIF(SUM(CASE
WHEN Header 1 = '01-Sales' THEN Actual Custom
ELSE 0
END) OVER(), 0)

Thanks.