Currently Being ModeratedFeb 4, 2013 12:30 PM (in response to Southerngirlmom)
Only photos added to the camera roll after enabling photo stream are added to your photo stream (not existing photos). Photo stream is designed to sync your photos across all your devices, not to serve as a backup. Photos are only held in your photo stream for 30 days, but they will stay in your My Photo Stream album on your device until you delete them or turn photo stream off for any reason (such as by restoring your device or you turn photo stream off in settings). To save your photo stream photos, regularly import your photos from the camera roll to your computer (photo stream photos originate from the camera roll), as outlined here: http://support.apple.com/kb/HT4083.