try ncftpput instead?
http://www.ncftp.com/ncftp/doc/ncftpput.html
"The purpose of ncftpput is to do file transfers from the command-line without entering an interactive shell. This lets you write shell scripts or other unattended processes that can do FTP. It is also useful for advanced users who want to send files from the shell command line without entering an interactive FTP program such as ncftp. "
nate
Yeah, but lftp do sync, that's my point.