Problem importing since start 2013

Hello everybody,

First here is my configuration

- version of iPhoto.

i photo 11 v 9.4.2

- version of the Operating System.

OS lion

I have the french version so i hope the translation will be good (and mmy english understandable) !

Since 2013, when i import pictures from my iphone or from a card (via usb), they are appearing in "last importation" (dernière importation in french) as usual but not in 12 last months (file "12 derniers mois").

When i do another photos import, those previous photos disappear from iphoto.

I haven't deleted nor installed anything and it really seems that it has to do with 2012 / 2013.

There is no message error.

I really don't know what to do.

Thank you for you help.

Marie