Unfortunately, this means the person you intended on referring joined under someone else, or hasn't verified the welcome email yet.
In the case of the intended referral has already joined, the last referral link click before the actual sign up is awarded for the referral. Some visitors to Webtalk decide to explore around the internet and social media getting more information on the company prior to joining. However, if they click content or ads posted by other members in the process, it will overwrite the cookie stored for any previous referral link clicked.
If the person you intended on referring has not invited anyone to join Webtalk since they joined, you can ask them to deactivate their account and create a new Webtalk account under you.