Why is there no diff option in my Review Board site?

I successfully setup Review Board according to the steps detailed in the following site: https://www.reviewboard.org/docs/manual/2.0/admin/installation/linux/ It is working perfectly except that it doesn't have diff options and I can't see where I can load a patch file. I just can load a regular file.

I also get the following message when I try to load a file: You won't be able to add any diffs to this review request. The review request will only be usable for reviewing screenshots and other graphic files.

Here is a screenshot:

Solution

I found an answer to my own question. It turned out that I must login as admin and navigate to the admin section and then add a cvs or svn repository then in this case I can load diffs and download them.