Problems with Groovy Script in Grails Project

Hello,

I am using IDEA 8.1.3 build #9886 with its bundled JetGroovy plugin v8.0, with Grails release 1.1.1. I'm a absolut newbi in IntelliJ and Grails.
I created a grails project where everything works fine. But starting Groovy Scripts in this project leads to the following Exception.

Exception in thread "main" java.lang.ClassNotFoundException: org.codehaus.groovy.tools.GroovyStarter

Path might be allright becaus if I create a "normal" Java Project it is no problem to run a Groovy Script. Thanks for help in advance.

M.