when agent version is bigger as server version an 400 error is generated. This is not the case here.
The url is not correct => server=http://ocsinventario.mydomain.com
You must have server = http://ocsinventario.mydomain.com/ocsinventory
The url is not correct => server=http://ocsinventario.mydomain.com
You must have server = http://ocsinventario.mydomain.com/ocsinventory