Can't change a Display Layout

Hello everybody, I’m using the Xibo API. I’ve a Xibo Player installed on an Ubuntu machine. Using manually the XCMS, I can easily change any layout I want. Anyway, when I’m using the API, I try to use the Postaman call as indicated into the API introduction. Actually, on the Display, there is no Layout. I simply want to play a new layout.
I do:

The response says that the command has been sent to the Player. Anyway, the Layout hasn’t changed. Where is the problem? The only thing I can imagine is a XMR problem.
The XCMS is executing on, while the player is on
I have this settings:

Yes, I know that is not a public address, but the only thing I can insert into the settings is Public Address…

Is that the problem?
How can I solve it?