Calculated measure on New model

Sorry if it's an easy one, but I don't know how to do it:

I have a NEW SAC model with a chart account that builds a P&L. (let's say Gross-sales, COGS and Gross profit)
I have a measure of "VALUE" and I would like to create a calculated measure that will take every line in my "value-P&L" and divide it with gross sales

I just don't find how to write it - I've made few trials more or less like the one below, (with resultlookup or lookup) but they were not valid - I must miss something:

thank you
Deb

[VALUE]/[d/ACCOUNT]="GROSS_SALES"