PKAddPassButton Localization on device language change

Lets say I got two preferred device languages( english first,italian second). I got a PKAddPassButton, which label gets the english localization on first install, but if I change the device language to Italian and relaunch the application, the buttons label has the english translation despite changing the first preffered device language to italian. I need to re install the application to get the italian string on the button. Is there anything I may be doing wrong?