Version already exists

I’m rather new to add-on making; but I checked everywhere I could think of but could not find the answer to my add-on problem.

I’ve written this simple add-on of which I wanted to upload a new version. I’ve updated the version number in package.json and subsequently in install.rdf.
When I upload my new version to the developers hub I first select my new file on which I get positive validation upon uploading.
But when I click on the ‘add version’ button I get: Version 0.0.x already exists.
I am at a loss about what I do wrong or what to do now.

It sounds like you’re clicking on the version and then in the Add File button, which would lead to an error. You should use the Add Version button. If the version is higher than the previous one, there shouldn’t be any problems. If there are, I suggest you email amo-admins AT mozilla DOT org with all the details.