No prompt to Push after commit. Commit not pushed.

[sachelis]

I am running SourceTree 4.1.3 on a Mac. 

When I:

1. Stage files that have changed.
2. Enter a commit message.
3. Leave the "Push changes immediately..." checkbox UNchecked.
4. Click the Commit button.

No error messages are displayed, but the Push button doesn't show a number (I'd expect a "1") and the commit doesn't appear on bitbucket.org. The History in SourceTree does show the commit with a commit number.

If I follow the same steps as above but do select the "push changes immediately..." checkbox, I get a "src refspec refs/heads/HEAD does not match any" error as shown here (in bold):

git --no-optional-locks -c color.branch=false -c color.diff=false -c color.status=false -c diff.mnemonicprefix=false -c core.quotepath=false -c credential.helper=sourcetree commit -q -F /var/folders/fc/1_ybtrqn5h54w29tft3l1fpm0000gn/T/SourceTreeTemp.89CL9b  

git --no-optional-locks -c color.branch=false -c color.diff=false -c color.status=false -c diff.mnemonicprefix=false -c core.quotepath=false -c credential.helper=sourcetree push -v --tags --set-upstream origin refs/heads/HEAD:refs/heads/HEAD 

Pushing to https://bitbucket.org/USERNAME/REPOSITORYNAME.git

error: src refspec refs/heads/HEAD does not match any

error: failed to push some refs to 'https://bitbucket.org/USERNAME/REPOSITORYNAME.git'

Completed with errors, see above

Here is the History tree that is displayed in SourceTree:

Thanks for helping a git novice!