Memcached seems to be not working. How to verify and fix this?

Hello community,

i installed redis and memcached to my zammad 5.X.
I tested my installation with

memcdump --servers=localhost

On my first Server this will throw back lots of results, but on my second server not.
Both Servers are exactly on the same version. Now i need to verify why memcached is not working on one of the servers.