XL Connect 7 Error (User "xxxx" not found. ....)

I just installed XL Connect 7 on one machine. When I used and tried to create a table (Company). I got the following error:

User “xxxxx” not found. Please contact your administrator to be added to the authorized users.

The machine has XL connect 5 installed, and XL Connect 5 works fine.

Anyone has this issue before? Please help.