RBK13 (RBR10 & RBS10)

Customer has a RBK13 (RBR10 & two RBS10) and attempting to add two more RBS10's.  Attempted to sync these via the app & the web interface, "Setup Failed".  I power cycled, paperclip reset, refuses to sync.  Is their a limit to the number of satellites you can add?  No issues with the original two RBS10's.