No photo stream

Does your MacBook meet all requirements described here?

http://support.apple.com/kb/HT4486

To use Photo Stream, including Shared Photo Streams, you need an iCloud account, compatible devices, and up-to-date software:

• iPhone, iPad, or iPod touch with iOS 6.0 or later
• Mac with OS X Mountain Lion v10.8.2 or later and iPhoto 9.4 or Aperture 3.4 or later
• PC with Windows 8, Windows 7, or Windows Vista (Service Pack 2) and the iCloud Control Panel 2.1 or later for Windows
• Apple TV (2nd generation) with Software Update 5.1 or later

You can still use Photo Stream without Shared Photo Streams if your devices meet these requirements:

• iPhone, iPad, or iPod touch with iOS 5.1 or later
• Mac with OS X Lion v10.7.5 or later and iPhoto 9.2.2 or Aperture 3.2.3 or later
• PC with Windows 7 or Windows Vista (Service Pack 2) and the iCloud Control Panel v2.0 or later for Windows
• Apple TV (2nd generation) with Software Update 5.0 or later

For complete iCloud setup instructions, visit How to set up iCloud.

And have you tried to enable the Photo Stream like this?

On your Mac, go to System Preferences > iCloud and select the checkbox for Photo Stream. Click the Options button to verify that both My Photo Stream and Shared Photo Streams are enabled. Then, open iPhoto or Aperture to confirm that My Photo Streamand Shared Photo Streams are turned on in the application you want to use with Photo Stream. You can also adjust your Photo Stream settings in iPhoto or Aperture Preferences.

Regards

Léonie