Subsribers unable to access content

Hiya. In the past 3 days I've had 2 subscribers claim that they are not able to access the content right after subscribing. My transaction records show that they paid. The one thing that the 2 subscribers have in common is that no user name is coming up for them in the transaction record. What might be the problem here, and how can I help these customers of mine access the content?? Thank you for your time.