iPhoto '11 won't automatically startup and import my iphone 4 camera photos

I bought a new Macbook Pro 2.9 GHz Intel Core i7, and was able to import the pictures from my iphone 4 automaticallyto iPhoto. Now 2 months later, iPhoto won't startup or import any of the photos taken on my phone, but it syncs my music, tones, apps, etc. What can i do to import my photos again?