I know these are all obvious, but have you checked these:
1. Is this a default instance of SQL (in which case your "Server Name" above is correct), or is this a named instance?
2. Are you sure the port is 1434? Use the SQL Server Config Manager (SQL Native Client, Client Protocols, TCI/IP, Default Port) to verify.
3. Also try without any port number specified.
4. Are you sure the username and password are correct? Try using these credentials in SSMS to verify they work.