"Unable to complete requested action because the rpt package does not contain any rpt content" Error

Summary:

I am getting this error when trying to preview a report package:

"Unable to complete requested action because the report package does not contain any report content."

Content (required):

I have a reference doclet that is pulling a report with a chart. All content has been enabled. I can preview the single doclet and get it to show up, but when I try to run the entire report package I get the above error.