Cannot run Scala through ProcessBuilder

When I try to run

processBuilder = new ProcessBuild开发者_开发百科er("scala", "-classpath", CLASSPATH, CLASSNAME);
process = processBuilder.start;
process.waitFor;

within an Scala application on Eclipse Helios IDE, it yields the

java.io.IOException: Cannot run program "scala": CreateProcess error=2, The system cannot find the file specified.

I've already configured the Windows system environment variable Path and scala runs OK on Windows command line. I've also added the variable Path into Eclipse run configuration.

I suspect the problem here is that you need to pass scala.bat, not scala. To narrow down the problem, you should try running other programs, to see what you can or cannot run.