Invalid DER-encoded CRL data java

Question

I am trying to check if x509 certificate is revoked or not:

CertificateFactory cf = CertificateFactory.getInstance("X.509");
X509CRL crl = (X509CRL) cf.generateCRL(crlFile);
if (crl.isRevoked(certRSA)) {
    System.out.println("REVOKED");
} else {
    System.out.println("NOT REVOKED");
}

and getting this Exception:

java.security.cert.CRLException: Invalid DER-encoded CRL data
    at sun.security.x509.X509CRLImpl.parse(X509CRLImpl.java:981)
    at sun.security.x509.X509CRLImpl.<init>(X509CRLImpl.java:144)
    ....

How can I convert that crl file into DER-encoded crl file? Thanks!