Calculate Averages

Good evening, I hope you are well, I turn to you to consult the following:

I have this measure, which allows me to get sales totals for the years 2019, 2020, 2021.

the second measure allows me to get the sales averages for each year and month.

although when I create the model and place the measures in the matrix, it calculates the monthly averages, but in the final total throws another amount that is not the total of the average per month and year, I would like to know if you can help me to be able to clear this doubt, of why it does not calculate correctly, I remain attentive, mcuahs grcias.