Greetings Apple friends,
I, too, had this problem. The solution that worked best for me was:
1. Plug your device into your Mac
2. In iTunes, click your device in the left column
3. In the tabs for your device, click Photos
4. Ensure these settings are the way you would prefer
If you are still unable to access your Photo Stream pictures on your iOS device:
5. In iPhoto, create an Event and title it something like "Photo Stream as of mm/dd/yy"
6. Import your most updated Photo Stream pictures into this newly created Event
7. Perform steps 1 - 4 and ensure that this specific event is selected to sync with your iOS device.
This will get those photos on your device but it will not update because it is simply an Event and not Photo Stream itself. To update, you'll need to import any new photos into the "Photo Stream as of mm/dd/yy" Event in iPhoto, update the date in the Event title, and sync with your iOS device.
I posted this because I couldn't figure out a way for my iPhone's Photo Stream to update with the photos that it says there are in my iPhoto's (on my computer) Photo Stream. Hope this helps some of you out!
- M