This error will appear when a sub-user on an account has reached their configured cap on the number of new mobile sites that they can create.
Contact the administrator or owner of the MoFuse account.
- Log into your MoFuse account
- Click on the 'Users' link to bring up the list of sub-users
- Click on the Edit/Pencil Icon
- Configure the '# of New Sites' value as needed. Raising the current value should resolve the above error for that particular sub-user.