Excel in Dax

Thanks for your answer. 

I managed to find what I was searching for, using another formula.

You're right, my calculate is very much a "this row and the previous row", however, each row has a specific criteria and regarding the amount of data I can't use such a formula. Also I wanted to have a sum of two average, here what I did:

To succeed I created two new columns, excluding all the values except those which were matching my criteria (using = IF('Table'[xxx]="abcd";'Table'[yyy];0) ). In addition to that, I created a matching key (='Table'[zzz]&'Table'[www]&'Table[vvv])

Then, I wrote a measure 

Average of 'Table'[uuu] by MatchingKey =
AVERAGEX(
KEEPFILTERS(VALUES('Table'[MatchingKey]));
CALCULATE(SUM('Table'[uuu]))
)

This made the sum of the average of values matching the same criterias. 

I don't really know whether this is the simpliest solution but it works :)