Mismatch errors found

I have created two sample projects to test out backstopjs, but I am failing on both with error of "Mismatch errors found" when I run the `backstop test` command.
After installing it globally I ran the `backstop init` command that created the backstop_data folder and its subfolders on my root.

Then I executed the `backstop test` but it returns with missmatch errors and loads the html report in the browser. But the bitmaps_test director is never created either.
On one of the sample projects I ran has the same project structure and content as the one on https://css-tricks.com/automating-css-regression-testing/ site, but using the `backstop test` instead and executing the command on the root. The scenarios code is also the same as suggested on that page. So the url path is the same as suggested on that page.

Any suggestions what I may have done wrong?