failed to connect with proxycommand

[kc334]

The ssh connection to my remote server needs a proxy. This is my ssh config
Host ddd-xxxxxxxxxxxxx HostName ddd-xxxxxxxxxxxxx User root ProxyCommand C:\Users\KK\proxyclient.exe connect --region-id=xxxx --instance-id=xxxx --config-file=C:\Users\KK\.proxyclientconfig ServerAliveInterval 15 TCPKeepAlive no IdentityFile C:\Users\KK\.ssh\id_rsa
When I tried sshfs-win:
C:\Users\KK>net use Y: \\sshfs.k\root@ddd-xxxxxxxxxxxxx
I get response:
System error 59 has occurred. An unexpected network error occurred.

I can login to my server using ssh root@ddd-xxxxxxxxxxxxx.
I tried sshfs-win on another remote server which does not need ProxyCommand, and it worked
Have anyone gotten this issue