The username you have configured within AT2Sage (Tools > Options > Sage) is already logged into Sage Accounts elsewhere.  You must log out of Sage Accounts using that username before using AT2Sage.

If you are not logged into Sage Accounts using that username anywhere on the network the user may have become locked.  To unlock the user, log into Sage Accounts using the username configured within AT2Sage, Sage should let you know that the user is currently logged in and give you the option to unlock the user, click yes to unlock the user.  Once the user has been unlocked close down Sage Accounts and try connecting again using AT2Sage

To avoid such problems we recommend you create a new user within Sage Accounts that AT2Sage may use exclusively.  To do this follow the instructions below:

1. Log into Sage Accounts with the username Manager
2. Go to Settings > User Access Rights
3. Click New and create a new user name AT2Sage, assign a password if required
4. Give the user full access
5. Close out of Sage Accounts
6. Open AT2Sage
7. Go to Tools > Options > Sage
8. Type in your new username and password into the box provided