HT4906 I cannot select photo stream on my imac

Question

how can I turn on photo stream on my iMac.  I can get to the screen that should allow me to select but cannot click on it.

Answer 1

Log out of iCloud in the System/iCloud preference pane and disable Photo Stream in iPhoto's Photo Share preference pane.  Then log back in and re-enable, respectively.  That should jump start Photo Stream.
If that doesn't work do the following and then repeat the above:  make a temporary, backup copy (if you don't already have a backup copy) of the library and try the following:
1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your
     User/Home/Library/ Preferences folder.
2 - delete iPhoto's cache file, Cache.db, that is located in your
     User/Home/Library/Caches/com.apple.iPhoto folder. 
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3 - launch iPhoto and try again.
NOTE: If you're moved your library from its default location in your Home/Pictures folder you will have to point iPhoto to its new location when you next open iPhoto by holding down the Option key when launching iPhoto.  You'll also have to reset the iPhoto's various preferences.
NOTE 2:  In Lion and Mountain Lion the Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and hit the Enter button - 10.7: Un-hide the User Library folder.
OT