System doesn't create the internal order when the service document is released.
Document flow is correctly updated but the internal order number wasn't generated
you added entries in the customizing option "Define Custom Handler Classes for Forward Data Exchange". Now you have the corresponding entries for the standard documents , e.g. SRVO and your ZRVO. This means that object BUS200116 (Service Orders) will execute twice standard classes like CL_CRMS4_PROC_SRVORDER_FWD and try to generate twice the internal order.
KBA 3273411 - Message KO 104 Order does not exist in Service documents
Delete the entries added for your own documents.