event ID 20071 when adding gateway server

Deaers,

I'm trying to add 2 gateway server one with suffix .com domain and the other .local

I did the same steps for both Exactly i succeeded on  .local but on .com i have received event ID 20071 "The OpsMgr Connector connected to , but the connection was closed immediately without authentication taking place.  The most likely cause of this error is a failure to authenticate either this agent or the server .  Check the event log on the server and on the agent for events which indicate a failure to authenticate.

I checked the registry and the serial number is the same the FQDN of MS is correct and i can ping using FQDN

i followed 2 articles here you are.

http://technet.microsoft.com/en-us/library/bb735413.aspx

http://technet.microsoft.com/en-us/library/hh456445.aspx

Any help? Thank you