(1) in the Assignment Type field, did you select "Upload Single File"?
If this is set instead to "Offline Activity" or "Online Text" there will not be an upload link.
(2) If the "Available from" or "Due date" parameters make the assigment currently unavailable, the upload link will not be visible.
If this is set instead to "Offline Activity" or "Online Text" there will not be an upload link.
(2) If the "Available from" or "Due date" parameters make the assigment currently unavailable, the upload link will not be visible.