Unable to import an ECC_NIST_P256 asymmetric private key to KMS

I am creating the key using

openssl ecparam -out ec-private-key.bin -outform DER -name prime256v1 -genkey -param_enc explicit

Followed in the instructions mentioned in importing-keys-encrypt-key-material to encrypt the key and try to import it but it fails with the error : ImportKeyMaterial request failed: InvalidCiphertextException

Steps followed:

• Download wrapping public key and import token from AWS console
  • Wrapping key spec: RSA_4096
  • Wrapping algorithm: RSAES_OAEP_SHA_256
• Encrypt key materials using openssl pkeyutl -encrypt -in ec-private-key.bin -out EncryptedKeyMaterial.bin -inkey WrappingPublicKey.bin -keyform DER -pubin -pkeyopt rsa_padding_mode:oaep -pkeyopt rsa_oaep_md:sha256 -pkeyopt rsa_mgf1_md:sha256
• Upload the EncryptedKeyMaterial.bin and ImportToken.bin to KMS console.