For an SAP Add-In system, you must perform the following checks before further investigations:
The SAP resources running the ABAP and Java Central Services instances are in the same Service Group.
The SAP resources running the ABAP and Java Enqueue Replication server instances, are in the same Service Group.
The EnqSrvResName attribute of the Java Enqueue Replication server instance is set to the VCS resource that is running the corresponding Java Central Services instance (SCS).
The EnqSrvResName attribute of the ABAP Enqueue Replication server instance is set to the VCS resource that is running the corresponding ABAP Central Services instance (ASCS).