To post a course on Coursemill you would have to have converted your course to be SCORM compliant. In doing so, the system auto generated an AU - equal to a SCO. Look directly under the course title in the tree. To be SCORM compliant, you can not reference objects outside of the AU. If you only have one AU, check to see if you have placed objects under the course title level. If so, move them under the AU. If you have multiple AUs, you can not reference objects (text, graphics, videos, audios, etc.) from one AU to another. You'll have to copy the repurposed objects to each AU and fix the references within the AUs.
