Caclulating Inventory based on initial Inventory

[dats]

Dear PowerBi Community,

I have a retailer sales table containing data from anuary 2020 to June 2023:

-purchased product per retailer/month

-sold products per retailer/month

-initial inventory per retailer/ based on January 2020

Basically I would like to calculate a running total inventoy based on the initial inventor and latest purchased and sold products

The issue is that  I cannot get the correct running total calculation(Column: my calculation). I beleieve it is a context issue.

Year Month	Purchased goods	Sold goods	Delta	Initial Inventory	MY calculation	needed solution
2020 Jan	5	2	3	7	10	10
2020 Feb	5	2	3		3	13
2020 Mrz	5	2	3		3	16

Can anybody help out on this? 

kr,

dats