Difficulties in receiver function as a transmitter but top

Use the Aventree Saturn along with a B-Speech RTX1 for BT transmission to the aux in my stereo.
They were so far not completely compatible, as the Aventree only as a transmitter (B-speech receiver) function. Anders rum they did not pairing up.
Since the Aventree ohnehn is more compact but also with battery and funktoniert (by the way even though it depends on the power), which is not a big problem for me.
Otherwise, both worked well right away.