When you successfully upload a file to an assignment you will see a green checkmark in the Submission window. You must wait for that green checkmark. Don't browse away from the page while your assignment is being uploaded:
If you wait, but don't get the green checkmark, here are some things to try:
- Clear your browser's cache & cookies.
- Update your browser to the latest version.
- Use Incognito mode, which disables browser extensions. Chrome instructions. Firefox instructions. As of 2017/1/16, the LastPass extension to Chrome is known to cause problems uploading to assignments.
- Try a different browser.
- Try a different computer.