Q: Why airdrop doesn't run on my iMac 2011 with the new os x yosomite?

Read here:

OS X Yosemite: Use AirDrop to send files to devices near you

AirDrop will work between your Mac and another Mac compatible with AirDrop ("Legacy AirDrop"):

"To transfer files between two Mac computers, you need one of the Mac models listed below and OS X Lion or later.

MacBook Pro (Late 2008 or newer)*

MacBook Air (Late 2010 or newer)

MacBook (Late 2008 or newer)*

iMac (Early 2009 or newer)

Mac Mini (Mid 2010 or newer)

Mac Pro (Early 2009 with AirPort Extreme card, or Mid 2010)

*The MacBook Pro (17-Inch Late 2008) and the white MacBook (Late 2008) do not support AirDrop."

AirDrop cannot be used between your Mac and iOS devices:

"In order to transfer files between a Mac and and an iPhone, iPad or iPod touch, your iOS device needs iOS 7 or later installed and your Mac needs to be a 2012 or later model."

From Use AirDrop to wirelessly share content

Hi John

I have two questions. My MacBookAir mid2011 can receive call but can't make call. the message is :

I already use same iCloud account on my iPhone6 and MacbookAir ( 10.10 Yosemit)

2- My Text Message forwarding doesn't work and not showing code on my Mac.

Thank you for your help

That is terrible.  That certainly was not the expectation generated by Apple.  Very disappointing.