namecoin name_firstupdate
Unfortunately you didn't provide enough information:


Which OS?
Version number of your Namecoin server?
Does this Namecoin server run on your local machine? If not, how is it connected physically?
Did you apply any command line params when starting the server?
What is the content of your namecoin.conf file?


Generally speaking, the most common causes for RPC connection problems are:


Mismatch of the provided data (rpcuser, rpcpassword, rpcport) with the contents of namecoin.conf
Command line parameter -server is missing