fix

AddressBook.cpp

@@ -544,7 +544,7 @@ namespace client
 		if (dest)
 		{
 			auto datagram = dest->GetDatagramDestination ();
-			if (!datagram)
+			if (datagram == nullptr)
 				datagram = dest->CreateDatagramDestination ();
 			datagram->SetReceiver (std::bind (&AddressBook::HandleLookupResponse, this, 
 				std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4, std::placeholders::_5),