Why won't my message signature verify

Question

Can anyone help. I dont seem to be able to verify a signature that I have just created. I'm a Java and Crypto newbie so please take it easy on me! The code is as follows:
import java.nio.ByteBuffer;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Signature;
public class EncryptionLesson  {
     public static void main(String[] args) throws Exception {
          ByteBuffer message = ByteBuffer.wrap("This is my message".getBytes());
          // Create key pair
          KeyPairGenerator kpg;
          kpg = KeyPairGenerator.getInstance("DSA");
          kpg.initialize(512);
          KeyPair pair = kpg.genKeyPair();
          // Sign a message
          Signature sig = Signature.getInstance("DSA");
          sig.initSign(pair.getPrivate());
          sig.update(message);
          ByteBuffer messageSignature = ByteBuffer.wrap(sig.sign());
          // Verify signature
          Signature vsig = Signature.getInstance("DSA");
          vsig.initVerify(pair.getPublic());
          vsig.update(message);
          if (vsig.verify(messageSignature.array())) {
               System.out.println("Signature Okay");
          } else {
               System.out.println("Signature NOT Okay");
}The result is alway "Signature NOT Okay". Please excuse the gratuitous use of ByteBuffer, I have just read JavaNIO and was sold on them.

Answer 1

sorry about mistaking the vaiables in the previous post. the proper main will look like this:
public static void main(String[] args) throws Exception {
          ByteBuffer message = ByteBuffer.wrap("This is my message".getBytes());
          // Create key pair
          KeyPairGenerator kpg;
          kpg = KeyPairGenerator.getInstance("DSA");
          kpg.initialize(512);
          KeyPair pair = kpg.genKeyPair();
          // Sign a message
          Signature sig = Signature.getInstance("SHA1withDSA");
          sig.initSign(pair.getPrivate());
          sig.update(message.array());
          ByteBuffer messageSignature = ByteBuffer.wrap(sig.sign());
          // Verify signature
          Signature vsig = Signature.getInstance("SHA1withDSA");
          vsig.initVerify(pair.getPublic());
          vsig.update(message.array());
          if (vsig.verify(messageSignature.array())) {
               System.out.println("Signature Okay");
          } else {
               System.out.println("Signature NOT Okay");
     }Futher to bring it to your notice, this is signing and verification and not encryption ;-) you might consider your class name!