Setting up Rsync credentials

[Turboproc]

Having some challenges to setup Rsync and especially the credentials in the way it's supposed to work. What I do is

1. Create SSH credentials
2. Copy the public key to the remote host
3. Create SSH connection using the private key created above
4. Create RSync taks (syncing from user root to user root, using (not sure) the previously created SSH connection
5. Start the task
6. failing with error

But, in case I copy the public key which is in /root/.ssh/id_rsa.pub towards the remote host it does work.

Impression I get is that in the case of following steps 1-6 eventually the wrong private/public keypair is used. Don't know how to fix this or how to debug to get more details.

Any suggestions?