BI 4.0 - Report can be viewed, but when scheduled/ran I get DB 18456 error
I have a report deployed to CMC that was migrated from a BOXI R2 environment. In the R2 environment the report was created against oledb driver, deployed and we ran it against an ODBC SQL Server data source. Everything was fine. Report could be previewed and scheduled/ran.
After migrating the report to SAP BI 4.0 using the deployment tool, I can view the report in 4.0 CMC fine which means that the report can establish a connection to the database. I could verify this by changing the data source name in ODBC admin in windows and it didn't work, so I know it was using the connection.
The strangest thing is that when I run the report (Right click > Schedule or Right click Run Now) I get this error:
Error in File ~tmp1bc86f443c2ea80.rpt: Unable to connect: incorrect log on parameters. Details: [Database Vendor Code: 18456 ]
This error seems to suggest that I didn't provide the correct logon parameters or that I am not authorized to access this database (correct me if I'm wrong). However it doesn't make sense because the exact same parameters were used for Viewing the report which works.
I verified a thousand times that the login info in Database Configuration is correct. I'm out of ideas. I expected this migration to be rather smooth since we're going only 2 versions up.
Anyone? Much appreciated.
BI 4.0 is running on Windows 2008 Server 64 bit.