Resources disappear in itunes U course

I am having difficulties with my first iTunes course manager.Last night I populated my first course with about 20 materials - docs, weblinks, books. Then this morning only 4 remained. Thought it hadnt saved them so re-added them. Then all of a sudden everything was back, including the duplicates! So I removed the duplicates and proceeded to add more materials and edit their descriptions. Hey presto - suddenly all I had "edited" was missing again.Only those materials uploaded without changes/editing

HELP !