IntelliJ "Debug info unavailable" - how to fix?

I have a Java Tomcat web application built in IntelliJ that calls code in another module called "Stuff". I've attached the source of the relevant code to "Stuff" so I can step into it and hit b开发者_Go百科reakpoints, but I cannot see variables or their values. Watches don't work either. All I get is "Debug info unavailable".

How do I see the debug info?

Please compile using the following options:

javac -g:source,lines,vars

I guess it's related to this question. Make sure the classes are compiled with the debug info. It can be tuned in Settings | Compiler or if you build from Ant, you need debug=on attribute for the javac task.