Can't install update Smash Bros

Hi. Im using FBI and i can't install any update for smash bros (usa cia) it says always says: Invalid Signature (0x6a)
I am trying to install the usa update 1.1.5 but it doesnt install, also I was testing with other cias and are allways installed without any issue.
Ive tried every method but it doesnt work, I hope you can help me please