Hi Wolfgang,
I would recommend not using the map, if you are just mapping that one parameter from the flat file schema to your SQL adapter request schema.
Basically, you can make both fields as distinguished fields, in both flat file and SQL adapter request schemas, and assign one to another in a Message Assignment shape with the following line of code (beforehand, you would declare two orchestration-level messages with their types respectively from the Flat File schema and the SQL Adapter request schema):
SQLAdapterSchemaMessage.Record.DistinguishedField = FFSchemaMessage.Record.DistinguishedField;
Then, in the same flow of your orchestration, you would have a logical Send shape and a logical Receive shape linked to a logical two-way Port that represents the call to your SQL adapter (which you would configure in the Administration console).
Does this scenario make sense to you?
Daniel.