Node-red-opcua-client: Local own certificate is not used


i am trying to connect a raspberry pi 3b with a siemens s7-1500 using the opcua server-client-connection. I got node-red v2.0.5 and node-red-contrib-opcua v0.2.236 installed. Trying to connect to the PLC, I get the Error:

1 Sep 10:49:51 - [info] Flows werden gestartet
1 Sep 10:49:51 - [info] [OpcUa-Client:26b75b0ddabff64d] 	Local 'own' certificate is NOT used.
1 Sep 10:49:51 - [info] Flows sind gestartet

Any idea how i can solve this problem?

Thanks and best regards