The domains (SymbolList is domain) are provided by the source/service. The message you see means that from the service that you consume, for the instrument you are requesting, SymbolList domain is not available. Within a consumer you can not turn on domains, you can only select a domain that is made available by the service.
If the source is a custom provider, then within your custom source you have the complete control of domain models to implement and to make available to the consumers of the source.
We're trying to address a similar use case as follows:
1) We have a Java UPA/ETA Publisher application (i.e. it acts like TREP) that can respond to a client initiated SYMBOL DOMAIN request with a list of instrument names per the API.
We're able to validate that a Java UPA/ETA client consumer application and can a symbol domain request and receive the corresponding symbol list
2) What we are unable to figure out, is how to configure the ADH to issue the symbol domain request similar to what we can do via the Java API as a client per the above. The ADH configuration opens a RSSL channel, etc. and is able to correctly send instrument requests etc. but we cannot get the symbol domain request working.