Can you connect using any other SSH client? Can you ping the SFTP server from the datacenter? What happens if you run "telnet sftp_server_ip 22"?
I have a lab top running Windows 7 Professional 32 bit and I can connect to SFTP server using username and password no Private Key file protocol SFTP,Port 22 and allow SCP fallback. However I loaded WINSCP on a Windows Server Datacenter 64 bit and using same credentials I can't connect I get the error "Network error: Connection Refused"
Please help what is the problem.