Commands for successful domain controller replication on Ubuntu / Samba4 / Zentyal

I have a Primary Domain Controller (PDC) and an Additional Domain Controller (ADC) running on two different machines at two different locations connected via a VPN. Both are running a version of Ubuntu with Samba4. I'm having trouble getting changes to replicate from DC to DC, but most of my trouble is only one way. I have determined that the correct way to initiate a replication from PDC -> ADC is to send the following command FROM THE ADC: sudo net rpc share migrate files sysvol \ -k --destination=ADCserverName.companyname.local \ -S PDCserverName.companyname.local --acls \ -U "companyname\\AdminAccountName" ...and this works pretty well. What is not working is my ADC -> PDC replication. And furthermore, I am not sure about what command I should issue FROM THE PDC to initiate an ADC -> PDC replication. Would it be the EXACT SAME COMMAND with simply the --destination= and -S reversed? Full disclosure: I'm running the two Domain Controllers on Zentyal Community Edition 3.5. I have tried getting help from the forum there: https://forum.zentyal.org/index.php?topic=23294.0 but the response so far has been zero. As I understand it Zentyal is merely a customized version of samba4 running on top of Ubuntu with a nice GUI. So I thought I might get a generic answer related to samba here.