dtFTPJ SFTP API connectivity issue

We are unable to connect SFTP server using edtFTPJ SFTP API

However, we are able to connect the same server using following command
sftp -v -o PubkeyAuthentication=no -o "Proxycommand=/usr/lib/ssh/ssh-socks5-proxy-connect -h socks-proxy-server.com -p 1080 1xx.7.2xx.1xx 22" user@1xx.7.2xx.1xx

Please note,The connectivity fails,if i remove PubkeyAuthentication=no from the above command
sftp -v -o "Proxycommand=/usr/lib/ssh/ssh-socks5-proxy-connect -h socks-proxy-server.com -p 1080 1xx.7.2xx.1xx 22" user@1xx.7.2xx.1xx

I would highly appreciate your help in this regards.

[support2]

Can you please post the code you are using to connect, together with the DEBUG level log file.