My affiliate's links or clicks are not working, what could be the problem?
This could be due to a number of reasons, the most likely cause is that they had visited your website before, without any affiliate link. By having done this, they may have an old "cookie" on their computer. To enable successful testing from their own browser, you need to advise them to clear or delete their cookies for your domain (where the link is going to).
After that, they should be clear and ready to go back to your website, with their Id in the URL. This will create a fresh new cookie, and the click / sale will register in the control panel.
If that does not work, it could be that the cookie which they need to delete is located somewhere else. Each browser is different. They need to check their specific browser specifications and properly delete the cookies (and possibly their CACHE files).