Error Permission denied publickey assistance

[Morgan Whitlock]

I have linked my SourceTree to BitBucket and have everything set up, however when I try to Fetch or Push it will not allow me and comes up with "

Permission denied (publickey).

fatal: Could not read from remote repository.

Please make sure you have the correct access rights

and the repository exists."

I do not understand what is asking as my fellow colleagues who are working alongside me are not having the same issue, and I wish to solve this ASAP. So any assistance would be appreciated.