Couldn't connect to Docker daemon at http+unix://var/run/docker.sock - is it running?

Docker Compose raise error below.

$ docker-compose up Couldn't connect to Docker daemon at http+unix://var/run/docker.sock - is it running? If it's at a non-standard location, specify the URL with the DOCKER_HOST environment variable.

$(docker-machine env MACHINE NAME) solved the problem.

$(docker-machine env dev)

docker-machine hang at Waiting for VM to start...

I've installed docker-machin on Mac OSX(10.8.5), and it hangs up at  Waiting for VM to start... when start docker machine.
Then I've upgraded Virtual Box to 4.3.24 and rm stacked docker-machine and created a new docker-machine.
That solved the problem

http://stackoverflow.com/questions/27614056/osx-boot2docker-hangs-on-waiting-for-vm-and-docker-daemon-to-start#28782567