Some assignments may allow you to overwrite your previous submission more then once until the assignment’s due date.
This option to resubmit your paper may be allowed by your module instructor only and on an assignment-by-assignment basis.
If resubmitting please note that you are allowed three attempts where the Similarity Report will generate immediately. After three attempts, it takes up to 24 hours before a new Similarity Report can be generated.
Also, the assignment settings may be preventing you from submitting your paper. If the due date has passed and your assignment does not allow for late submissions, you will not be able to submit.
If you are attempting to resubmit, it is possible that your assignment settings only allow for one submission per student.