Can't push or pull despite existing rep and ssh key added

Hi,
Here is what it says :
" Please make sure you have the correct access rights and the repository exists.
spatphyto@marvellous-otter:/media/CMBCEBack2/Rpackages/r-package-bioagresseurs$ git pull
Load key "/home/spatphyto/.ssh/id_dsa": Permission denied
Permission denied (publickey).
fatal: Could not read from remote repository."

I can't figure out what happens. The ssh key is added and the repository does exist...
Any idea ?
Thanks