Port 1433 is disabled on the SQL server or there is a firewall preventing port 1433 from being used to communicate with the SQL server.
The SQL Server Configuration Manager provides basic configuration management for SQL Server services, server protocols, client protocols and client aliases.
On the SQL Server Instance you will need to ensure the TCP/IP Protocols is listening on port 1433 for the TCP port. You may also need to list this port for the TCP Dynamic Ports.
If you have changed this port for some reason, you will need to deploy a custom script for the verification section in SureBackup. After performing the script change in production, please perform another backup job for verification.
Confirm the status of this port by performing "netstat -ban" on the masqueraded SQL server, from the command prompt.
For information on deploying a custom script please review this Veeam article: http://www.veeam.com/KB1312