No Content Input Area

I just installed WPMU onto an existing site. On my second site, when I go to add a new post or a new page, I can not enter any content for the page.

I am able to enter a title. There is also an Add Media button. However, none of the other things usually on the page appear. There is no post option box, no featured image, etc. And there is no text area to write the actual post. Clicking on “screen options” does nothing, so it doesn’t seem to be something where they are just hidden.

Any idea why this is missing?