Incorrect Sales Contribution Percentage

Hi everyone. I am working on a Power BI report and need help with a specific DAX calculation. I'm trying to calculate the sales contribution percentage for each product category within a specific region, based on the top three customer segments. However, I seem to be getting incorrect results with my current DAX formula. Here's what I've tried:

Sales Contribution Percentage = DIVIDE( SUM('Sales'[Sales Amount]), CALCULATE( SUM('Sales'[Sales Amount]), TOPN(3, 'Customers'[Customer Segment], SUM('Sales'[Sales Amount]), DESC), 'Regions'[Region] = "North" ) ) * 100

Could you please review the DAX formula and suggest any necessary corrections or alternative approaches to achieve the correct calculation of sales contribution percentages?

Thank you!!!

-Kate