OTMM Mobile App configuration - Proxy creation error

Hello,
i'm trying to configure and OTMM installation, release 16.3, to interact with a 16.2.1 AppWorks Gateway but when i run the utility config-for-gateway-app.sh i get this error:

Exception Debug: Creation of OTMMAPI Proxy definitions in OTAG failed
Exception Message Id: message.error.gateway.otag.proxy.create.failed
Exception Message: Creation of OTMMAPI Proxy definitions in OpenText Application Gateway failed.

The app has been succesfully installed in the gateway and the two hosts, gateway one and otmm (with otds) one ping each other.

Can anyone please give an advice on this issue?

Thanks, best regards.
Andrea