Certificate signature verification using Bouncycastle (J2ME)

Good day. I have a problem again. I want to verify signature using this
code:

// there is Base64.decoded byte array in tmp..
ASN1InputStream a = new ASN1InputStream(tmp);
DERObject obj = a.readObject();
ASN1Sequence seq = (ASN1Sequence)obj;
a.close();

X509CertificateStructure cert = new
X509CertificateStructure(seq);

// Getting the signature. It's correct
byte[] signature = cert.getSignature().getBytes();

// Getting pub key. It's correct too
SubjectPublicKeyInfo spki = cert.getSubjectPublicKeyInfo();
RSAPublicKeyStructure rsapub = new
 RSAPublicKeyStructure((ASN1Sequence)spki
.getPublicKey());
RSAKeyParameters pub = new RSAKeyParameters(false,
rsapub.getModulus(), rsapub.getPublicExponent());

// Getting "to be signed" structure
TBSCertificateStructure tbs = cert.getTBSCertificate();

// !!!!!
// Maybe TBS structure NOT correctly decoded??
byte[] obg = tbs.getEncoded();


RSAEngine engine = new RSAEngine();
MD5Digest digest = new MD5Digest();

PSSSigner signer = new PSSSigner(engine, digest, 0);
signer.init(false, pub);

signer.update(obg, 0, obg.length);
boolean istrue = signer.verifySignature(signature);

Signatures doesn't match. i've got istrue = FALSE as result... What's
wrong? Help plz.
I also tried to sign TBS using the private key but signatures didn't
match anyway.