Cannot Add more users.

Hi, the repository currently has 4 users.

When I try adding another person to this repo, I get following error message.

Not enough users on plan. The owner of this repository (-------) will need to upgrade their plan before this action can be completed.

The following steps were taken which created this issue.

1. Sent invitation to a user.
2. There was a delay (for about 10 minutes for the invitation mail to be sent) on invitation.
3. Mistaking the delay as a bug, I've canceled pending invitation in order to resend.
4. Tried to resend invitation.
5. Got the following error message. "Not enough users on plan. The owner of this repository (-------) will need to upgrade their plan before this action can be completed. "
6. Waited 24 hours.
7. Tried sending the invitation again.
8. Still the same error message.

I've attached a screen shot of the error message on this issue.

Thanks in advance.