Flex : How to setup inter module dependency

I want to have two flex modules in one project

App1 - application type
Lib1 - library type

App1 depends on Lib1.

I am trying to setup a project but could not figure out how exactly it should be done.

I tried the following steps:

1. Create App1 module first (using default settings, meaning including autogenerated wrapper/compiler-config/HelloWorld).
2. Create Lib1 module but without adding wrapper/compiler/HelloWorld.
3. Link Lib1 to App1
4. Tried to refer to a class from Lib1 in App1 code but got compiler error "Access undefined property in ]]>"

Any pointers how to make it work?

Thanks,
Roman