SSH in git behind proxy on windows - FATAL: Connection closed by peer

Question

By a SSH connection, I'm trying to clone a Repository from a Company BitBucket which use 7999 port (not Bitbucket.org) using Git Bash. I've generated the RSA key and added the public key into my profile of the BitBucket Company and the keys re located in ~/.ssh, I've setup the proxy by using git config --global http.proxy http://userPrx:pwdPrx@ipProx:8080 (because I'm under the Company Proxy) and also I have setup my config file as this post suggest. Then, when I try to Test the connection I get this:

$ ssh -vT globaldevtools -p 7999
OpenSSH_7.3p1, OpenSSL 1.0.2j  26 Sep 2016
debug1: Reading configuration data /c/Users/MyUser/.ssh/config
debug1: /c/Users/MyUser/.ssh/config line 5: Applying options for globaldevtools
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 20: Applying options for *
debug1: Executing proxy command: exec /C/Users/MyUser/AppData/Local/Programs/Git/mingw64/bin/connect.exe -S IpProxy:8080 x.x.x.x 7999
debug1: permanently_drop_suid: 1104711
debug1: identity file /c/Users/MyUser/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /c/Users/MyUser/.ssh/id_rsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.3
FATAL: Connection closed by peer.
ssh_exchange_identification: Connection closed by remote host

This is my config file:

ProxyCommand /C/Users/MyUser/AppData/Local/Programs/Git/mingw64/bin/connect.exe -S IpProxy:8080 %h %p


Host globaldevtools
  User git
  Port 7999
  Hostname x.x.x.x
  IdentityFile ~/.ssh/id_rsa
  TCPKeepAlive yes
  IdentitiesOnly yes

I must indicate that in this file (config) instead of IpProxy:8080 I've tried with

http://IpProxy:8080
http://usrProx:pwdProx@IpProxy:8080
usrProx:pwdProx@IpProxy:8080

Do I have to do something else? Did I miss something? All help is appreciated.