groovy not working

I tried running the following groovy script without success

java.lang.Runtime r = java.lang.Runtime.getRuntime();
java.lang.Process p = r.exec("ruby C:\\ruby\\rubyFile.rb");
Thread.sleep(60000);

the ruby file is a watir script that goes to a web page and does a few things.
when I click run in soapui, it stalls for a few seconds but nothing happens.

I tried running the same rubyFile in cmd line and it works fine.

What could be the problem here?

Thanks in advance