iMessage stuck 'Offline'

[Big Stevie]

MacBook Pro 2012 Yosemite
iPhone 5 IOS 7

Having installed Yosemite onto my 2009 MacBook Pro I find that I'm not receiving iMessages. Even if I send a message to myself from my macbook it doesn't appear on my iPhone.

When I right click on iMessage in my dock its states its offline. Any idea please how I might get it online again? Surly it can't be because I haven't got IOS 8 on my iPhone?

Thanks

 

[Big Stevie]

Think I've solved this one myself.

Messages > Preferences > Accounts

If it says your not logged into your Apple account then log in. At the left of this box is a list of any email addresses used with iMessage. Click each one and ensure you tick 'Enable this account' for each one.

Seems to be working now.