fixed the issue. Will look into that further perhaps you can modify the entry of the gradle generated library by adding scala-library*.jar e scala-reflect*.jar It works but it's an ugly workaround (wich probably you will have ot do again and again when you change the project dependencies in the gradle file)
Error: scala: No 'scala-library*.jar' in Scala compiler library
should help you out Since IDEA 13 you should use SBT support which is bundled with Scala plugin. With it there is no need to add third-party SBT plugins and run special commands; just import the project using "File -> Import project..." menu item, and it will automatically load SBT project structure and its dependencies.