Sage 200 Evolution

I can place order via freedom API but I want to edit existing order and place invoice from existing order What is the schema for updating existing order ? Endpoint to place invoice from existing order: http://127.0.0.1:5000/freedom.core/DATABASENAME…

I am using Evolution 200 v 11.0.3.0 and configured the freedom Api sdk according to the Sage Evolution Freedom API Guidelines V2.01. Everything seems fine except for the CustomerTransactionPost wich returns the error "Object reference not set to an instance…