Failed to join domain through Azure's VPN

HI there,

I take advantage of Azure as our Active Directory DR site. I configured a VPN between our office and Azure.

I deployed a Windows Server 2012 R2 vm in Azure, installed ADDS on it and joined this vm to our existing domain in our office . When I promoted this vm to a domain controller, the prerequisite check I always got the following error message.

Verification of outbound replication failed. Error reading the options property of the NTDS settings. Unknown error (0x8000500c)

It was ok to join our existing domain through VPN, but it always stopped at this error message and failed to be promoted as a domain controller. Is there anything I should do to the VPN?

Douglas