Help with multicast receive

[Nuno Magalhaes]

I've build an application that sends UDP packets to a multicast address
224.1.2.3 but in my other application I can't receive that packets
using the code below. It blocks on receive. Any suggestions? (I can see
the packets arriving at 224.1.2.3:554 on the client machine since I'm
running the server and the client on the same machine)

UdpClient uc=new UdpClient(8899);
uc.JoinMulticastGroup(IPAddress.Parse("224.1.2.3") );
IPEndPoint ep=new IPEndPoint(IPAddress.Any,0);
byte[] packet=uc.Receive(ref ep); -----> Blocks!!!
uc.Close();