Git pull says no address associated with name

I have put my project
git pull git@bitbucket.org:arkebi/aatma.git

then I am getting this error
ssh: bitbucket.org:no address associated with name
fatal:The remote end hung up unexpectedly

Can u help me in this case
address is correct
I have used that dozens of times
I just changed from windows 7 to windows 8 and finding this error