Attached Javadoc in ADT SDK is displayed only for some classes

Hi everybody!

I'm trying to explore the ADT SDK a bit. I have attached Javadoc to the 3 libraries I'm using in my project (com.sap.adt.project.ui_2.36.1.jar, com.sap.adt.project_2.36.1.jar, com.sap.adt.sapgui.ui_2.36.2.jar) as it is described in http://scn.sap.com/docs/DOC-59944 (Getting started with the ABAP in Eclipse SDK).

The problem I'm facing is that for some classes (like AdtSapGuiEditorUtilityFactory) the Javadoc is displayed correctly:

But for others (like IAdtSapGuiEditorUtility), even thought these are in the same package, it is not displayed;

I just get the message: Note: The Javadoc for this element could neither be found in the attached source nor the attached Javadoc.

Is there something I forgot to set up?

Thanx for help!

Have a nice day!

Ondrej