FHIR Response to Data Message Class Question/Issue

I am trying to create a HS.FHIR.DTL.vR4.Model.Resource.Encounter message based on a conversion of HS.FHIRServer.Interop.Response QuickStream to a JSON %Dynamic Object. 

When I try to send the HS.FHIR.DTL.vR4.Model.Resource.Encounter onto the Router

1. it is not showing up as a Defined Message Class to Route the message back to the SourceConfigName of the Request message that initialized the FHIR query
2. I keep getting "ERROR <Ens>ErrBPTerminated: Terminating BP EPIC.FHIR.Process # due to error: ERROR #5002: ObjectScript error: <SUBSCRIPT>%SaveData+29 ^Ens.MessageHeader.1 ^Ens.MessageHeaderI("MessageBodyId","{"resourceType":"Encounter","id":"xxxxxxxxxxx","id> ERROR #5002: ObjectScript error: <SUBSCRIPT>%SaveData+29 ^Ens.MessageHeader.1 ^Ens.MessageHeaderI("MessageBodyId","{"resourceType":"Encounter","id":"xxxxxxxxxxxxxx","id"

my inital design was to create a way to use FHIR calls like we do with other Web Services to query the External Repository, send back the result, and do something with the Result in the HL7 messaging.

Am I going about this all wrong? What have others done to Query FHIR from an External Source?