A: 

This may sound like a strange question, but are you really passing "url" literally in

createSeleniumClient("url");

"url" is no valid url and so I'd expect Selenium to complain here.

Heiko Rupp
oh sorry, i do have a valid url in there, i just didn't put it in.
JLau
A: 

Have you made sure that you have both the Selenium server jar and the java client jar from the same version? I accidentally had server version 0.9.2 and client jar 1 beta and was getting this error. Making sure I was compiling with the 0.9.2 client jar fixed the issue for me.

A: 

Have you verified that the network server that you're trying to execute the tests on is running the Selenium Server? The error looks like the RC code is having trouble connecting to the server to start the tests...

I'd suggest trying to execute the tests manually on the build machine at first in order to ensure that everything is configured properly.

Peter Bernier
Thanks, I have already resolved this problem.
JLau
How did you solve this problem?
Ula Karzelek
A: 

JLau, How did you resolve this problem? I am running into the same problem. Thanks.

A: 

JLau, can you please post the solution here, as I'm also facing the same problem while executing selenium RC test cases on linux machines via ant build script.

Bhushan