[Python] Python <-> C via sockets

I'm probably missing something rather obvious, but is there a known
problem with getting a Python based socket program to communicate with
a C based socket program? A simple echo server written in Python
(the example from Python in a Nutshell actually) will happily talk
to a Python based client. If a C based client is substitued the connection
is refused (or so the C client reports). The C client will talk to
a C server.