The delete instructions do not work for some of my iPhone photos, photos which I have taken with the iPhone....they can be deleted from my Mac, from my wife's phone, and from our iPad Air but when I select them on my phone the trash icon becomes greyed out and unavailable, can't find any answer to this from Apple's user guide or FAQs, any ideas? I've tried turning off iCloud sharing on the phone, turning it back on, makes no difference.