No Audio Output Headphone Jack connected

I bought a 3,5 Audio Plug cable to Dual Chinch for my Amp.
If i use my Samsung S10 i get directly Audiooutput,
if i use my Picopix Max Headphone out nothing is happening only the
Speaker of the ppm is playing further ?
Is it defective ? Must is switch something in the Software, for normal not.
I use it for the first time, only standing above my bed. 10 times used till now.
To make sure i disconnected a FireTV stick which i did no use.
Also i use normal Youtube and other Apps that output to the internal speaker,
but nothing happens if i use the Headphone out, the internal Speaker plays further.
Also i use two other Headsets, nothing happens.
It`s defective i think.
What is the service Email for this situation, how long does the repair takes and
where i have to send it to ?
Need Help…
Walter (Cologne/Germany)