Java Security

Hi all!

I�m trying to encrypt and decrypt using AESLight from Bouncy Castle to provide cryptographi to my mobile application. I encrypt the text with no problems, and sometimes i decrypted with no problems to!
But, with some messages i got the follow exception:

org.bouncycastle.crypto.InvalidCipherTextException: pad block corrupted
	at org.bouncycastle.crypto.paddings.PKCS7Padding.padCount(Unknown Source)
	at org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher.doFinal(Unknown Source)
	at softcomex.sfw2go.server.seguranca.TranslatorAESLight.processMsg(TranslatorAESLight.java:40)
	at softcomex.sfw2go.server.Waiter.sendMessageToClient(Waiter.java:251)
	at softcomex.sfw2go.server.Waiter.run(Waiter.java:211)

My class that uses AESLight:

public TranslatorAESLight (byte[] key, boolean cripto)
	{
		this.keyAES = new byte[16];
		System.arraycopy(key, 0, this.keyAES, 0, key.length>16?16:key.length);
		
		this.cripto = cripto;
	}

And, when I have to encrypt/decrypt i call the method processMsg:

public byte[] processMsg (String msg)
	{		
		byte[] msgReturn = null;
		int length = 0;
		
		BlockCipher engine = new AESLightEngine();
		BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(engine));
		KeyParameter key = new KeyParameter(keyAES);
		cipher.init(cripto, key);
		
		msgReturn = new byte[cipher.getOutputSize(msg.getBytes().length)];
		length = cipher.processBytes(msg.getBytes(), 0, msg.getBytes().length, msgReturn, 0);
		
		try {
			cipher.doFinal(msgReturn, length);
		} catch ( Exception e) {
			e.printStackTrace();
		}
		
		return msgReturn;
	}

Please, there is something wrong with this code?

Thanks.