Actionscript: Flexunit: unit testing existing actionscript project

Question

I was reading this: http://stackoverflow.com/questions/366088/flexunit-with-pure-actionscript-project-in-flex-builder-3/3472839#3472839

I am trying to do option 2 in his question. I have an existing actionscript project. I created a flex project with flexunit 4 setup and it runs. I set the flex project to have an external source library which is the actionscript project. The IDE and intellisense can see the classes in the actionscript project, but I get compile-time errors saying:

1046: Type was not found or was not a compile-time constant: testsource. FlexUnitTests/src/sampleSuite/tests TestCase1.as line 26 1281656208497 323

1172: Definition test:testsource could not be found. FlexUnitTests/src/sampleSuite/tests TestCase1.as line 5 1281656208498 325

1180: Call to a possibly undefined method testsource. FlexUnitTests/src/sampleSuite/tests TestCase1.as line 26 1281656208498 324

Am I missing something?