OpenSSL get Private and Public Key Function return False

Question

I want to encode and decode my data using Laravel PHP-JWT package. which require Private and Public Key in string format.

Therefore, I have created the certificate.pem by converting .crt to .pem format using below command

x509 -inform DER -outform PEM -in cert.crt -out certificate.pem

As openssl_pkey_get_private and openssl_pkey_get_public accept certificate in .pem format as parameter and Return Positive Key Resources.

Note: Positive Key Resouces is resource id='588' type='OpenSSL key' in debugging.

/* Path to certificate */
$path = storage_path('test/certificate.pem'); 

/* Extract the private key from $res to $privKey */
$privKey = openssl_pkey_get_private($path);

/* Extract the public key from $res to $pubKey */
$pubKey = openssl_pkey_get_public($path);

Query 1: Returning false in both $privKey and $pubKey

Query 2: Will JWT::encode accept as a parameter these Key Resouces object which is returning from OpenSSL function?

Is there any alternative?

Edit 1: I have OpenSSL enabled in phpinfo.

Edit 2: openssl_error_string output.

$path = storage_path('test/certificate.pem'); 
$private_key = openssl_pkey_get_private(file_get_contents($path)); // resource id='565' type='OpenSSL key'
$public_key = openssl_pkey_get_public(file_get_contents($path)); // false
$pubkey_error_message = openssl_error_string(); // "error:0909006C:PEM routines:get_name:no start line"