The connection agent datasource is using an SQL account that has the ability to read from the required database table (sa account in this instance).
Check that TCP/IP protocol is enabled in SQL Server. This isn't always enabled by default.
In SQL Server 2005 TCP/IP is set as follows:
Select Microsoft SQL Server 2005>Configuration Tools>SQL Server Configuration Manager. In the SQL Server Configuration Manager select the node SQL Server 2005 Network Configuration>Protocols for SQLSERVER. Right-click on the TCP/IP node and select Enable. Restart the SQL Server service. Right-click on the SQL Server service in Services and select Restart.
General for any Connection errors. The errors are standard jdbc errors and common to many applications. 'googling' the error details will usually show you many similar issues other users have experienced along with a range of answers that have been of use to other users in the past
