Save to Github > cannot publish project page

Hi, I want to save a wiki to Github and then publish a website from my repository. To do so, I followed @Mohammad s tutorial and saving to my rep has been working fine so far. But publishing is not as easy as described, I only get a 404 error when I check my reps url https://username.github.io/repository/. The setting for my source folder is definitely right (I double checked) and I also tried with a subfolder just to see if that would help. The Github help docs only describe the case of adding a page to the account, but not to the individual repository. Has anybody experience with that and could help?