Your subject may not use Turnitin for this assessment.
See: Where do I find the Turnitin link on my vUWS page?
Your file may be too large or in an unacceptable format.
You may be trying to submit a file format which is not acceptable according to Turnitin's assessment settings. For more information on the file types that Turnitin accepts, please see this FAQ.
Your assessment due date may have passed.
See: How do I submit a late assessment via Turnitin?
Check with your subject coordinator if you experience other issues.
For technical help with Turnitin, please contact ITDS via Live Chat or fill in their 'Something's Broken' form.