Can some one please explain the steps required to configure a multicast in Ubuntu? I have a simple program taken from Internet. I get errors when I execute the client program. I get the error as:

Opening datagram socket....OK.  
Setting SO_REUSEADDR...OK.  
Binding datagram socket...OK.  
Adding multicast group error: No such device: 

When I execute the server program I get the error as:

Opening the datagram socket...OK.
Setting local interface error: Cannot assign requested address

I am using Ubuntu to run the program. I have two different laptops but connected via the same network. I am using wireless network to perform the above operation.