ITune song won't add to playlist on iTunes or?

Any devices! When I try to drag it to any of the listings, I get that little 'reject' circle. When I plug my iPhone in or iPods… It says It can't be synced. It will play on iTunes, just that it won't add to either playlist on iTunes or any devices? How do I get it to do this?

From the picture above…
Is the list on the right your MUSIC LIBRARY? Or another playlist…

You can only add songs from the MUSIC list from the very top of the left column…
as in this photo:
https://www.dropbox.com/...GqD-nHaVl0