Interfaces not found (Error #1045, #1046)

First, I sinned, by doing horrible things like developing a whole flash-website
with all code attached to frames and movieclips, without using one class.

Then I read things about OOP (like senocular’s writings on
and about design patterns (Moock’s lectures on his site: Observer and [URL=“”]MVC).

Now I want to try my luck by scripting an AS-driven game, combining all this wisdom.
Before I will do that, I am trying to take over the example Moock gave on the page
where he explains model-view-controller (just so I get the hang of mvc)
It is a simple clock application, mvc-style. And here we have arrived at the problem.[INDENT][SIZE=2]The Problem: The compiler cannot find certain interfaces.[/SIZE]
[/INDENT]For example, the first error message I get when testing/debugging is the following:

“1045: Interface IObserver was not found.”

This error comes from “AbstractView”, in the class definition (… implements IObserver …)

package mvc
    import util.IObserver;
    import util.Observable;
    public class AbstractView implements IObserver, IView
        //I am pretty sure the problem has nothing to do 
        //with the content of my classes/interfaces.

So we check IObserver, and nothing seems to be wrong there too.

package util
    import util.Observable;

    interface IObserver

When I just delete “IObserver” from “AbstractView implements IObserver, IView”,
the error does not appear any more (which is expectable).

But then the compiler goes further into the code,
and spits out other errors who are similar.
For example:
1046: Type was not found or was not a compile-time constant: IController.
in ClockTools or in ClockAnalogView (classes from the mvc-clock example).

My folder/packages structure:

-> clock
      - all clock classes
      - ...
-> mvc
-> util

I have no real clue what could be the problem.
I have taken file/folder access into account, but all files/folders have
full write/read permission and are not hidden.

This whole mess is kind off a disappointment in my first real steps
into oop and design patterns.
Therefore I would really like some help or opinions about this.