Error no pem block while enrolling the Fleet Server with encrypted private Key

hello,

We are getting the following error while enrolling the fleet Server: " "message":"Fleet Server - Error - 1 error: no PEM blocks"

elastic-agent enroll --force \
        --fleet-server-es="https:elasticsearch_node:9200" \
        --fleet-server-service-token=########################################################### \
        --fleet-server-policy=fleet-server-policy \
        --fleet-server-cert=/etc/elastic-agent/certs/certificate.cer \
        --fleet-server-cert-key=/etc/elastic-agent/certs/certificate.key \
        --fleet-server-cert-key-passphrase=/etc/elastic-agent/certs/passphrase \
        --fleet-server-es-ca=/etc/elastic-agent/certs/certificateauthorities_ca.cer \
        --certificate-authorities=/etc/elastic-agent/certs/certificateauthorities_ca.cer  \
        --url=https://fleetServer_node:8220```

With unencrypted private key the command works!

We are using elasticsearch 8.11.3 Version

Could you please help us?