Event ID 3759 error when adding new server to SPS 2010 server farm

Hi,

I am creating SPS 2010 server farm. I installed SPS 2010 on WFE server. The installation went through successfully. Both portal site and central admin site show up correctly. Without changing anything I try to install the SPS 2010 on APP server.

The installation on APP server went through without error. After trying to join the existing SPS 2010 server farm, I got the following error message in ULS,

Database 'SP_ConfigDB' on SQL Server instance 'SPS2010' is not empty and does not match current database schema.

 Also the same error showed on event log as Event ID: 3759

I am using farm service account to deploy SPS 2010 on APP server, and the account has the following permission,

1.      In local administrator group

2.      Sysadmin and dbcreator permission of SQL server

I can't find a solution, any ideas?

Thanks in advance.