imessage not displaying all that is on ipad and iphone

The answer is both YES! OK if el capitan can't sync with icloud - ok. But some messages that I composed with iPhone are displayed in el Capitan. Weired!

Yes, that is all set up as it should. What is weird is that some text messages are displayed on the iMac (El Capitain) even with emojis, and others are not.

aha ! it says message forwarding requires Yosemite or newer, therefore El Capitan is out. But why do i still receive some messages on El Capitan, that I don't understand.

Well - after a restart of the entire system, all messages are back. It sometimes helps to restart, though I havent the faintest idea what gave it the hiccup