I had the same problem and searched the forum and no steps helped but peiced together some advice and here is what worked for me:
1) unplug my phone from computer
2) quit iTunes and iPhoto
3) pluged it back in and iTunes automatically launched saying a passcode is required to communicate with the phone (I didn't turn that on so I had to create one on my phone). Error that is was unable to communciate to my phone.
4) I set up a passcode on my phone.
5) A window popped up on my phone asking if I trusted this computer. Allow.
6) iPhoto automatically launched and my photos were there!
* For some reason, step 3 & 5 kept repeating and I couldn't get rid of these pop-up windows but I didn't care, I was able to download my photos from iPhoto.