In my case, i have cross checked the server and credentials with Filezilla utility first and checked the path of the directory to which i have to upload files. whatever the access the user get after logged into filezilla, we just have to use it like.. ( /dir/dir1/dir2 ) after IP followed by slash.
ex:
ftp://111.111.11.11/(directory path looks like into filezilla)
ftp://111.11.11.111/dir1/dir2/dir3
also i have updated
request.EnableSsl = false;
and it is working for me.