Why can't I check the Notes icon in the iCloud system pref?

Question

After upgrading my iMac on 11/19, I'm trying to get the Notes app to sync with iCloud, as I use my iPads' Notes app extensively at work.  When I open the iCloud system preference, the Notes app is checked at first.  It then becomes unchecked and when I try to re-check the box. system preferences quit unexpectedly.  I've also tried adding a note first on the iMac, and then going into iCloud system preferences, but get the same result.
Thanks in advance for your help,
Mike

Answer 1

OK, reading others posts about multiple accounts, I went into the Notes on my iPad, and clicked the Accounts button.  Sure enough, all of my notes on the iPad were under the account Yahoo.  Going into Notes on my iMac, and then going into Accounts under the Notes menu item, I only had iCloud and att.net.  When I chose the att.net account AND checked the Notes box, all of my iPad notes synced with the iMac.
I agree with a previous poster in another message, this is not made clear how to set this up.  I guess I lucked out that all 3 of my iPads are set up identically with regards to Notes, Accounts, and iCloud.
Hope this helps someone else.
Mike