Unable to get data using readRowsByEntry()

Hi
I am downloading data using
readRowsByEntry(obj,(billingCount-1),2); function but i am geeting error like unable to read object

Please check the issue
I am doing following steps

1) Connect with meter
2) create a boject for profile generic
GXDLMSObject obj;
obj = GXDLMSClient.createObject(ObjectType.PROFILE_GENERIC);
obj.setLogicalName("1.0.98.1.0.255");
obj.setVersion(1);
obj.setDescription("Billing Data");

readRowsByEntry(obj,3,2);

public Object[] readRowsByEntry(GXDLMSObject pg, int index, int count) throws Exception {
byte[][] data = mClient.readRowsByEntry((GXDLMSProfileGeneric)pg, index, count);
GXReplyData reply = new GXReplyData();
readDataBlock(data, reply);
return (Object[]) mClient.updateValue(pg, 2, reply.getValue());
}

public final byte[][] readRowsByEntry(final GXDLMSProfileGeneric pg, final int index,
final int count) throws InvalidKeyException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidAlgorithmParameterException, IllegalBlockSizeException,
BadPaddingException, SignatureException {
return readRowsByEntry(pg, index, count, null);
}

And so on.
\
PLease tell why i am getting error