AS3 project stopped working when I went from CS5 to CS6

I have a bunch of includes for displaying text:

import flashx.textLayout.elements.Configuration;

import flashx.textLayout.formats.TextLayoutFormat;

import flashx.textLayout.formats.TextAlign;

import flashx.textLayout.elements.TextFlow;

import flashx.textLayout.elements.ParagraphElement;

import flashx.textLayout.elements.SpanElement;

import flashx.textLayout.container.ContainerController;

and when I compile the project, I get this error:

Definition flashx.textLayout.elements.Configuration could not be found.

for all these includes.  And then I get the error:

Type was not found or was not a compile time constant: Configuration

When I try to use any of these types. 

Do I need to download additional libraries for CSS or put my project in a different file?  I don't understand why my includes shouldn't work - these classes are still showing up in the online AS3 documentation. 

I am running OSX 10.9.2.

Thanks!