Streaming meta node cannot be executed

Dear All,
in order to speed up the execution time of the workflow I wrapped the workflow into a metanode and set the “Job Manager Selection” to “Simple Streamin mode”. However, I am unable to execute the metanode and I received the following error message:
Subnodes must only contain native nodes in order to be streamed: Phase responses 2:1:684:0:557
Note that the wrapped metanode contains sub meta notes, variable nodes and nodes that are not configurable for streaming. Is this the reason why I cannot exucte the streaming meta node. Thanks for you support in advance.