Receiver interface not visible when building Sender/Receiver ID

Hello experts,

I see something strange...

I have a scenario, asynchronous, where I send an idoc out of the ECC 6.0 system to several files.

So I installed a multimapping, but this is done in a ABAP mapping.

In my Operation Mapping:

Source = idoc structure and Target = Inbound Asynchronous Service Interface.

So far so good. Also, the scenario works and multiple files are created on the operating system...

Next, I want to put some prioritities.

So, I go to transaction SXMB_ADM -> Configure Sender/Receiver ID

There, I want to configure a receiver, but my inbound service interface is not in the list.

And if I enter it manually, I get this error: "<Service Interface> is not an interface".

Please advice.

Thanks a lot.

Dimitri