Cloned repsitory with GitDesktop - SourceTree gets can't find error.

[KidsBookOutlet]

I just cloned a repository  to my local pc with Git-Desktop. When I made  a change and tried to push my commit to GitHub I got the error :

git -c diff.mnemonicprefix=false -c core.quotepath=false --no-optional-locks push -v --tags origin master:master
remote: Repository not found.
fatal: repository 'https://github.com/AbbottHMG/Solutions.git/' not found
Pushing to https://github.com/AbbottHMG/Solutions.git
Completed with errors, see above.

When I put the url - https://github.com/AbbottHMG/Solutions.git into my browser, the GitHub repository appears.

What could I be doing wrong.

Another repository I have is working fine???

Thanks

Abbott