LIFE_IN_MONTHS does not update in initial charge

I have charge hundred assets by FA_MASS_ADDITIONS table interface, some of the assets have a different life in months than the category; so I put this  life in months (number of months) in the fa_mass_Additions but when I charged it, it does not update the life of the asset, the asset inherits category's set up.

example:

Life in months for an asset: 1 year and 2 montsh, I put on FA_MASS_ADDITIONS: LIFE_IN_MONTHS = 14

Category set up LIFE IN MONTHS = 1 year

The asset is charged by the category set up.

In addition the method is created for 14 months = 1 year 2 months