No available subscription pools to list

Hello,

I used 2x4 servers. They are registered for several years then suddenly 1 machine is no more longer registered !

Now it is possible for me to register this Server again but
subscription-manager list --available --all
No available subscription pools to list

access.redhat.com/solutions/189533 is Ok
access.redhat.com/solutions/321033 is Ok

The license is valid :-)
Im Customer Portal this server is red ! Not Subscribed !

Many thanks for your Help and assistance
Dan