Jenkins pipeline cannot scp into remote server

Question

I've got

Hostkey verification failed

when running Jenkins declarative pipeline and using ssh agent (see logs below):

Started by user xxxx
[Pipeline] Start of Pipeline
[Pipeline] node
Running on Jenkins in /var/lib/jenkins/workspace/bank_demo_back
[Pipeline] {
[Pipeline] stage
[Pipeline] { (deployproduction)
[Pipeline] sshagent
[ssh-agent] Using credentials root (remote_credentials)
[ssh-agent] Looking for ssh-agent implementation...
[ssh-agent]   Exec ssh-agent (binary ssh-agent on a remote machine)
$ ssh-agent
SSH_AUTH_SOCK=/tmp/ssh-XXXXXXxxx/xxx.xxx
SSH_AGENT_PID=xxxx
Running ssh-add (command line suppressed)
Identity added: /var/lib/jenkins/workspace/bank_demo_back@tmp/private_key_xxxxxx.key ([email protected])
[ssh-agent] Started.
[Pipeline] {
[Pipeline] sh
+ scp /var/lib/jenkins/workspace/bank_demo_back/target/bank-demo-0.0.1-SNAPSHOT.jar [email protected]:

Host key verification failed.

lost connection
[Pipeline] }
$ ssh-agent -k
unset SSH_AUTH_SOCK;
unset SSH_AGENT_PID;
echo Agent pid xxxx killed;
[ssh-agent] Stopped.
[Pipeline] // sshagent
[Pipeline] }
[Pipeline] // stage
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
ERROR: script returned exit code 1
Finished: FAILURE

Below, you can see the code declaration of the stage and step used into the pipeline script :

stages {
        stage('deployproduction') {
            steps {
                sshagent(['remote_credentials']) {
                    
                    sh 'scp /var/lib/jenkins/workspace/bank_demo_back/target/bank-demo-0.0.1-SNAPSHOT.jar [email protected]:'
                }
            }
        }
    }

ssh credential named 'deployproduction' have been created using Jenkins GUI menu : Dashboare > Manage Jenkins > Credentials > Sytem > Global credentials(unrestricted) (click the link to see the screen shot of Jenkins GUI credential creation : enter image description here) I have past the remote server ssh private key "into enter directly" section.

REMARQUE : When running

scp /var/lib/jenkins/workspace/bank_demo_back/target/bank-demo-0.0.1-SNAPSHOT.jar [email protected]: 

into my local machine shell, this command is working.

I have spent my entire day working arround it. for example I tried to modify the syntax to see if it can ssh into my server ():

sshagent(['remote_credentials']) {
   sh 'ssh -o StrictHostKeyChecking=no -l xxx xxxx uname -a'
}

It returned : Failed to add the host to the list of known hosts

REMARQUE : Jenkins is istalled on my local machine and I want the jar file to be uploaded through a declarative pipeline step command. (I don't want to deploy it manualy)

Thank's for your time.